(;
GM[1]
SZ[19]
AW[dp][dd][qi]
AB[qd][od][pp]
TR[qi]
C[Problem 1. Black to play.  

How should Black attack the marked white stone ? ]
(;B[qk]
TE[2]
C[Correct Answer.  

The white stone is outnumbered three to one. In such cases, it is important for Black to press his advantage and immediately attack. In this position Black 1 is the correct direction; this move drives White toward Black's strong position at the top. ]
;W[qf];B[of]
C[Next, Black caps with 3 ... ]
;W[oi];B[ok];W[mi]
LB[kc:B][pq:A]
C[... the sequence to White 6 follows naturally. Black has build a moyo on the lower right in sente. He can next reinforce his position at the bottom with A or take up position at the top with B. <= ]
)
(;B[qg]
C[Failure.  

Black might make a checking extension from above with 1, but ... ]
;W[ql];B[qn]
C[... this stone is inefficient because it is too close to Black's strong enclosure above. In other words, Blacks stones are overconcentrated. <= ]
)
)
(;
GM[1]
SZ[19]
AW[qj][dd][cp]
AB[oc][qd][pp]
TR[qj]
C[Problem 2. Black to play.  

This time the marked white stone is under the star point. In which direction should Black attack ? ]
(;B[qh]
TE[2]
C[Correct Answer.  

The checking extension of Black 1 is the correct direction. The distance from the small knight enclosure is perfect and Black 1 and ... ]
;W[qm];B[qo]
LB[mq:A]
C[... 3 put severe pressure on White's stones. Later Black will aim to enclose the corner with A. <= ]
)
(;B[ql]
C[Failure.  

Black 1 is the wrong direction. ]
;W[qg]
C[White extends to 2 and, since this stone is two spaces from Black's corner enclosure, White's stones are not under much pressure. Moreover, Black's position below is thin. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][df][cn][dp][po][rn][qm][pm][on][nn][no][pb][nc][lc]
AB[fq][jp][pq][pn][qn][qo][ro][oo][op][np][qk][pf][pd][qc]
TR[no][nn][on][pm][qm][rn]
C[Problem 3. Black to play.  

White's marked stones in the lower right are vulnerable. How should Black attack them ? ]
(;B[ol]
TE[2]
C[Correct Answer.  

Peeping with Black 1 is severe. Next ... ]
;W[om]
C[... White must connect with 2. ]
;B[nl]
C[Black 3 is a vital point which prevents White from making shape in the center. ]
;W[ln]
C[After White jumps to 4, ... ]
;B[jn]
C[... Black attacks the whole white group with 5. ]
)
(;B[fo]
C[Failure.  

Locally, Black 1 is a strong move, but it only focuses on reinforcing Black's moyo at the bottom. ]
;W[ol]
C[White secures his stones by making shape with 2, and Black's attacking chance vanishes. <= ]
)
)
(;
GM[1]
SZ[19]
AW[gd][cd][cg][cp][mp][qp][pn][on][nm]
AB[ec][fe][eq][oq][oo][no][pl][pi][oc][qd]
TR[pi]
C[Problem 4. White to play.  

Black has just extended with the marked stone. How can White take the initiative at the bottom ? ]
(;W[pq]
TE[2]
C[Correct Answer.  

Attaching with White 1 robs the black stones of their base and gives White the territory in the lower right corner. Next ... ]
;B[mo];W[kp];B[ln]
LB[mo:2]
C[... Black has to run away with 2 and 4, but ... ]
;W[gq]
LB[kp:3]
C[... White jumps to 3 and extends to 5, mapping out territory along the bottom and attacking the black stone in the lower left corner. In addition, the black stones at the bottom right are still without a base. With two vulnerable positions under attack, Black is at a serious disadvantage. <= ]
)
(;W[ln]
C[Failure.  

Confining the three black stones with White 1 is a dubious move. ]
;B[qq]
C[Black attaches with 2 and ... ]
;W[rq];B[qr]
LB[gq:A]
C[... easily makes life in the corner after descending to 4. Even if White attacks the stone in the lower left corner at A, she can't expect a big profit. The sequence in the Correct Answer Diagram is superior to the one here. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dp][qf][qi][oi][dj]
AB[qd][od][of][ok][qk][pp]
LB[mi:A][dj:B]
C[Problem 5. Black to play.  

Instead of jumping to A as in the "Correct Answer of Problem 1" , White plays B on the left side. How should Black attack ? ]
;B[mi]
TE[2]
C[Correct Answer.  

Black attacks by capping with 1. ]
;W[nj]
C[White will run away with 2. Next, ... ]
(;B[ml]
C[... Black plays the knight's move of 3, ... ]
;W[mj];B[ki]
C[... then jumps to 5. The white stones are in trouble. Next ... ]
;W[li]
C[... White wedges in with 1, but, ... ]
;B[lh];W[lj];B[kh];W[kj];B[jj];W[jk];B[ij];W[kl]
C[... after the sequence to White 14, ... ]
;B[pq]
C[... Black secures the lower right corner with 15. ]
;W[hk]
C[After White jumps to 16, ... ]
;B[jp]
C[... Black builds a moyo at the bottom with 17. <= ]
)
(;B[ph]
LB[nj:2][mi:1]
C[Failure.  

After exchanging 1 for White 2, Black could gauge out White's base and take some territory with 3 ... ]
;W[pi];B[rg]
C[... and 5. But Black loses the initiative in the center, and he is left with bad aji in the upper right corner. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dj][cp][eq][qj][qm]
AB[pp][qo][mq][qh][qd][oc]
C[Problem 6. Black to play.  

This is a continuation of the "Correct Answer of Problem 2". How should Black attack the two white stones on the right side ? ]
;B[oj]
TE[2]
C[Correct Answer.  

Capping with Black 1 is the key point. ]
(;W[pi]
C[If White runs away with 2, ... ]
;B[rk]
(;W[qk];B[rl];W[ql];B[rm]
C[... Black will gauge out White's base with the sequence to 7. White's stones are now floating in the center, providing an easy target to attack.  <= ]
)
(;W[rj]
C[Variation.  

White could block at 4, but ... ]
(;B[qk]
(;W[pj];B[pk];W[ok];B[ol];W[nk];B[pm]
C[... with the sequence to 11, Black has secured the territory in the lower right. ]
;W[ni]
C[White still has to play 12 to secure her stones, so Black ends in sente.  <= ]
)
(;W[pk]
C[Variation.  

White could establish a position in the lower right by blocking at 6. ]
;B[pj];W[ql];B[ok];W[pl];B[qi];W[rl];B[ri]
C[With the sequence to 13, Black sacrifices two stones and builds a moyo in the upper right. ]
;W[sk];B[oh]
LB[rn:A]
TR[pi]
C[To secure his moyo, he must capture the marked stone by playing at 15, but he might first want to rob the white stones of their second eye by playing at A.  <= ]
))
(;B[ql]
LB[qk:@]
C[Variation.  

Instead of @ in Variations 1 and 2, ... ]
;W[pl];B[rm]
C[... Black could link up his stones to the bottom with the sequence to 7, but this strategy is a bit weak-spirited.  <= ]
)))
(;W[om]
LB[pi:@]
C[Variation.  

Instead of @ in the Correct Answer, White might jump to 2 here. ]
;B[rk]
C[Black again gouges out White's base by playing 3 ... ]
;W[qk];B[rl]
C[... and 5. ]
;W[ok]
LB[rm:B][rj:A]
C[White attaches with 6, but his stones are still eyeless, while the black stones at the edge can link up to their allies above or below with A or B. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dj][cp][eq][qj]
AB[oq][qp][pd][qh][ql]
TR[qj]
C[Problem 7. Black to play.  

The marked white stone on the right is isolated within Black's stronghold. How should Black attack ? ]
(;B[oj]
TE[2]
C[Correct Answer.  

Capping with Black 1 is severe. What happens if White tries to escape ? ]
;W[pi]
C[The diagonal move of 2 on the right is White's best chance, since Black is weaker there. ]
(;B[nh]
C[But Black continues to attack with the knight's move of 3. ]
;W[ph];B[qg];W[pg]
LB[ph:4]
C[White must now push with 4 and 6, ... ]
;B[qf]
LB[qg:5]
C[... inducing Black to play 5 and 7. ]
;W[ng];B[mg];W[nf];B[pf];W[of];B[mf];W[nd];B[ld]
C[After the sequence to 15, White's stones are still in trouble. For Black's part, he has strengthened his stones in the upper right and built influence in the center. In contrast, White has gained nothing. <= ]
)
(;B[ph]
TR[oj]
C[Wrong answer.  

Capping with the marked stone is a good move, but to continue by pushing up with 3 ... ]
;W[oi];B[oh]
C[... and 5 is the wrong direction. ]
;W[ni]
LB[qc:A]
C[White escapes into the center with 6. Black's territory in the upper left is still not secure, since a 3-3 point invasion at A still remains. <= ]
))
(;B[pi]
C[Wrong answer.  

The diagonal move of Black 1 is bad. ]
;W[pj];B[oj];W[pl];B[qm];W[ok];B[nj]
C[The sequence continues to Black 7, but ... ]
;W[ml]
C[... White's stones have made it into the open when she plays the knight's move of 8. Black has made little progress with his moves. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dp][qo][pb][nc]
AB[jp][pq][pk][pd][pf]
TR[qo]
C[Problem 8. Black to play.  

White has invaded Black's moyo with the marked stone. How should Black attack it ? ]
(;B[qp]
TR[pk]

TE[2]
C[Correct Answer.  

Since Black's marked stone is in place, he should first exchange 1 ... ]
;W[po]
C[... for White 2 ... ]
;B[np]
C[... before jumping to 3. The two white stones are now heavy and vulnerable. <= ]
;W[qm]
C[White will try to secure her stones with moves like 4 and ... ]
;B[rl];W[nm]
LB[po:]
C[... 6, but ... ]
;B[nk]
LB[oo:A][pk:5]
TR[po]
C[... Black can build up his moyo on the top by attacking with 5 and 7. White could also have played the marked stone at A, but her stones would still be vulnerable. <= ]
)
(;B[np]
C[Failure.  

Neglecting to exchange 1 for 2 in the Correct Answer and immediately extending to 1 ... ]
;W[rq]
TR[pk]
C[... would permit White to secure her stone with 2. Not only has Black lost the territory he should have gotten in the corner, his marked stone has lost much of its value because it is no longer attacking effectively. <= ]
)
(;B[qm]
LB[oo:A]
TR[pk]
C[Failure.  

Black 1 is usually a severe pincer, but, since Black already has a pincer in place (the marked stone), it is redundant. The usual response to Black 1 it to jump to A, but ...  

]
;W[qq];B[qr];W[pp];B[oq];W[rq]
C[... in this case White secures  her stones in the corner with the sequence to 6. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][nc][kc][ok][qk][ro][jq][cq][dp][fp]
AB[pd][pc][qi][oi][po][pq][lq][bp][cn][ck]
TR[ro]
C[Problem 9. Black to play.  

White has just slid under Black's corner enclosure with the marked stone. How should Black attack White's position on the right ? ]
(;B[qn]
TE[2]
C[Correct Answer.  

Black 1 and ... ]
;W[rn]
(;B[rm]
C[... 3 stop White from making eyeshape. ]
(;W[rl];B[qm];W[sm]
LB[rq:A][pk:B][rl:4]
C[White links up with 4 and 6, but even if she jumps to A, she doesn't have two eyes yet. Black is also threatening to wedge in with B. <= ]
)
(;W[qm]
TR[rm]
C[Variation.  

When Black blocks with the marked stone, White might cut with 4. But ... ]
;B[ql];W[pm];B[rk];W[pl];B[rl]
C[... Black can link up to his allies above with the sequence to 9. White is now split into two weak groups. <= ]
))
(;B[qm]
LB[rm:@]
C[Failure.  

The hane @ in the Correct Answer is the key move. It is a mistake for Black to extend to 3. ]
;W[rm];B[ql];W[rl];B[rk];W[rj];B[pk];W[qj];B[pj];W[ri]
C[White can live with the sequence to 12 and Black's moyo in the upper right has been erased. <= ]
))
(;B[rq]
C[Failure.  

Black 1 lets White ... ]
;W[qm]
C[... settle her group with 2. White now has nothing to worry about. ]
)
(;B[qp]
C[Failure.  

Black 1 here is also bad. ]
;W[qm]
C[White responds with 2. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dp][kq][nq][qj][nc][md][mf]
AB[cj][pp][pn][pd][pf][oc][kc][ke]
TR[mf]
C[Problem 10. Black to play.  

White has just jumped out into the center with the marked stone. How should Black play ? ]
(;B[pi]
TE[2]
C[Correct Answer.  

Black 1 is the key point. It keeps the white stones at the top separated from their ally on the right side. ]
(;W[pj]
C[White first exchanges 2 for ... ]
;B[oi]
C[... 3, then ... ]
;W[lg]
C[... returns to take care of her stones at the top by moving out with 4. ]
;B[jg]
C[Black attacks with 5, then ... ]
;W[li];B[oj]
C[... plays another move against White's stones on the right. It is hard to predict how this fight will continue, but the white stones on the right are being severely pressed and if White tries to save then, it could spill over and affect the five white stones at the top. <= ]
)
(;W[lg]
LB[pj:@]
C[Variation.  

Instead of @ in the Correct Answer, White might immediately play the diagonal move of 2. ]
;B[jg]
C[Black could first exchange 3 for ... ]
;W[li]
C[... 4, then ... ]
;B[pj]
TR[qj]
C[... quell the marked white stone with 5. Although this stone has some aji, Black can look forward to some profit on the right side. <= ]
))
(;B[lg]
C[Failure.  

In some positions ... ]
;W[mg];B[lh];W[mh];B[li]
C[... a wall with the sequence to 5 can be good strategy, but ... ]
;W[nj]
C[... here these moves enable White to link up her stones and isolate Black's stones in the upper right. Although they are strong enough to live, White will be able to make profit by threatening them. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][cp][cn][dq][eq][qn][qk][nc][kd]
AB[ep][fq][fp][jp][pq][qp][qi][pd][pc]
LB[pc:B][nc:A][kd:C]
C[Problem 11. Black to play.  

White has just extended to C. How should Black continue ? ]
;B[on]
TE[2]
C[Correct Answer.  

Black should cap at 1, ... ]
;W[ok]
C[... forcing White to jump to 2. ]
;B[oi]
C[This induces Black to reinforce his moyo above with 3. ]
;W[mk]
C[Jumping to 4 is natural. ]
;B[ic]
C[Black now invades the top with 5. ]
(;W[gc]
C[White has to play forcefully and pincer with 6. ]
;B[ie];W[jc]
C[If White attaches with 8, ... ]
;B[jb];W[kb];B[jd];W[kc];B[ke];W[le];B[kf];W[lf];B[lg]
C[... Black presses the white stones with the sequence to 17. ]
;W[ne]
C[White then makes shape with 18 and ... ]
;B[of]
C[... Black secures the upper right with 19.  <= ]
)
(;W[je]
LB[ic:5]
C[Variation.  

White 6 here is another response to Black 5. ]
;B[he]
C[Black jumps to 7 and ... ]
;W[gc]
C[... White pincers with 8. ]
;B[gd];W[fc];B[hc]
LB[gd:9]
C[Black makes shape with 9 and 11, after which ... ]
;W[de];B[ig];W[kg];B[ii]
LB[ig:13]
C[... Black attacks with 13 and 15. ]
(;W[ki]
C[After White 16, ... ]
;B[ne]
C[... Black secures the territory on the right with 17.  <= ]
)
(;W[ne]
C[If White 12 here, ... ]
;B[of]
C[... Black will play 17 here.  <= ]
))
)
(;
GM[1]
SZ[19]
AW[dc][ce][dq][co][cn][po][kh][mh][ni][nh][oh][ph][pf][qf][qi][qj]
AB[dn][dl][pq][kc][nd][pd][qe][ng][qh][pi][oi][nk][pk][qk][rj][ri]
TR[po]
C[Problem 12. Black to play.  

White has invaded inside Black's sphere of influence with the marked stone. How should Black respond ? ]
(;B[pp]
TR[po]

TE[2]
C[Correct Answer.  

Bumping against the white stone with Black 1 is the strongest move. ]
;W[qo];B[rp];W[no]
C[The sequence to 4 can be expected. Next, ... ]
(;B[mp]
C[... Black stakes out the territory at the bottom with 5. ]
;W[ol]
C[White's stones are still insecure, so she has to escape into the center. She peeps with 6, then ... ]
;B[ok];W[ln]
C[... jumps to 8. ]
;B[lp]
C[Black calmly defends with 8. ]
;W[ll];B[lk];W[kl];B[li];W[lh];B[kk];W[jl]
C[With 16, White is out into the center, but ... ]
;B[ij]
C[... Black 17 keeps the white stones above and below separated. <= ]
)
(;B[mq]
LB[mp:@]
C[Caution.  

Black 5 (@) in the Correct Answer is an important move. Black must not play 5 on the third line because ... ]
;W[ol];B[ok];W[lo]
LB[lq:A]
C[... White can jump to 8 and her stones are savely out in the open. Moreover, White is threatening the attachment at A, so Black might have to defend against it. ]
))
(;B[np]
C[Failure.  

The knight's move of Black 1 is the standard response to the white approach move, but ... ]
;W[qq];B[qr];W[no];B[mo];W[pr]
C[... White can make sabaki with the sequence to 6. <= ]
)
(;B[qp]
C[Failure.  

If Black 1 here, ... ]
;W[mo]
C[... White will jump to 2. Either way, Black's thickness above has been neutralised. <= ]
)
)
(;
GM[1]
SZ[19]
AW[db][eb][ed][fd][gd][lc][qf][qi][pm][qn][po][dp][dj]
AB[cb][bc][dc][dd][ee][fe][gc][nc][pd][qd][ql][qo][qp][pq][nq]
LB[ql:A]
TR[qf]
C[Problem 13. White to play.  

Black has invaded at A. How should White respond ?  

Note the presence of the marked White stone.  

[You will find a supplement to this Problem Diagram as "Problem 137"] ]
;W[rm]
TE[2]
C[Correct Answer.  

White 1 prevents Black from linking up to his stones. ]
(;B[rj]
C[If Black 2, White plays on top with 3 and ... ]
;W[qj];B[ri]
C[... Black crawls with 4. ]
(;W[qh]
C[White 5 is now the  key move, ... ]
;B[qk]
C[... forcing Black to come back to correct the defect in his position by playing 6, but ... ]
;W[ok]
TR[rm]
C[... White confines the black stones with the knight's move of 7. Since White 1 (the marked stone) is on the vital point, Black's stones have no chance of making two eyes. <= ]
)
(;W[qk]
LB[ri:4]
C[Failure.  

After Black 4 in the Correct Answer, White should not draw back to 5 here. ]
;B[qh]
C[Black would then hane at 6 and ... ]
;W[ph];B[qg];W[pg];B[rf];W[pf];B[rg]
C[... link up his stones with ones above with the sequence to 12. Black's invasion has succeeded. <= ]
))
(;B[pj]
C[Variation.  

Instead of trying to live on the side, Black might play on the outside with 2 here. ]
;W[qj];B[qk];W[rk]
LB[qj:3]
C[But after White 3 and 5, Black is left with three burdensome stones which can be easily attacked. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][dd][cf][dp][dn][jp][mp][pf][qf][qi]
AB[db][fc][ic][qe][pd][nd][pq][po][qk][ok]
TR[dn]
C[Problem 14. Black to play.  

White has just played the marked stone, leaving her three stones in the upper right to fend for themselves. How should Black attack them ? ]
(;B[oi]
LB[rh:A]

TE[2]
C[Correct Answer.  

Black 1 is the best way to attack in this position. Black now aims at A. ]
;W[nf]
C[White escapes into the center with 2, ... ]
;B[og]
C[... Black peeps with 3, then ... ]
;W[of];B[ld]
C[... defends the territory at the top with 5. This is a basic example of how to secure territory while attacking. White's stones on the right are still vulnerable. <= ]
)
(;B[nf]
C[Failure.  

Attacking with Black 1 and ... ]
;W[oi];B[mi]
C[... 3 is in the wrong direction. Black's aim is to build a moyo towards the left, but ... ]
;W[rk];B[rl];W[rj]
LB[jd:A]
C[... White secures her stones with the sequence to 6, leaving the black stones in the lower right thin. Next, White can aim at the shoulder hit of A to reduce Black's moyo. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cd][ec][mc][me][mg][pj][pi][qj][pk][mq][oq][pq][bp][bq][cm][cj]
AB[hc][kc][ke][kg][pc][qe][qg][oj][qk][ql][qo][op][np][dp][cq][gq]
C[Problem 15. Black to play.  

The white stones in the upper right are still eyeless. How should Black attack them ? ]
;B[nf]
TE[2]
C[Correct Answer.  

Black first peeps with 1, then ... ]
;W[mf];B[oh]
C[... makes a shoulder hit with 3 to split White into two groups. ]
(;W[oi]
C[If White 4, ... ]
;B[nh]
C[... Black extends to 5, leaving White with two isolated and eyeless groups. If White tries to save one of then, the other will fall. This is a good example of a double attack. <= ]
)
(;W[mi]
LB[oh:3]
C[Variation.  

In answer to Black 3, White might immediately jump out to 4. ]
;B[oi];W[pl];B[qm];W[nl]
C[The sequence continues to White 8, but ... ]
;B[mj]
LB[mp:B][nl:8][nk:A]
C[... Black leans on the white group at the top by attaching with 9. If White 8 at A, Black will still attach at 9. If Black needs more strength to attack the white group on the right, Black can also lean on the white group at the bottom with the forcing move at B. <= ]
)
)
(;
GM[1]
SZ[19]
AW[kc][rc][qd][qe][pf][pg][qh][pp][qo][nq][bp][cn][ck]
AB[dc][ce][ic][qb][qc][oc][pd][pe][of][jq][dp][cq][fq]
TR[kc]
C[Problem 16. Black to play.  

How can Black use his wall on the right side to attack the marked white stone ? ]
(;B[je]
TE[2]
C[Correct Answer.  

The knight's move of Black 1 is the most effective way to attack. The white stone at the top is now in a pinch. ]
(;W[ke]
C[Trying to break out into the center with White 2 seems reasonable, but ... ]
;B[kf];W[le];B[lf];W[ne];B[oe];W[mf];B[mg];W[ib];B[hb];W[jb];B[hc]
C[... Black can confine White to the top with the sequence to 13. ]
;W[mc];B[nb];W[mb]
LB[mc:14]
C[White barely lives in gote with 14 and 16, but ... ]
;B[dj]
C[... Black can now build a moyo in the center with the shoulder hit of 16. <= ]
)
(;W[le]
C[Variation.  

Against the knight's move of White 2, ]
;B[ld]
C[... Black attaches at 3. He then ... ]
;W[kd];B[ke];W[md];B[lf];W[lc];B[mf]
LB[dj:A]
C[... sacrifices this stone and confines White to the top with the sequence to 9. The white stones are alive, but just like in the Correct Answer, Black gets a thick wall and he can then create a moyo by attacking the white stone on the left with a shoulder hit at A. <= ]
)
(;W[jd]
C[Variation.  

The diagonal attachment of White 2 is not good. After ... ]
;B[id];W[ke];B[kf];W[jf];B[ie];W[lf];B[kg];W[le];B[lg]
C[... Black 11, White can't live because there are no defects in Black's position to exploit. <= ]
))
(;B[ie]
C[Failure.  

Jumping out into the center with Black looks like a normal move, but it is slack. ]
;W[ke]
C[White jumps to 2, and Black doesn't have a good follow-up, so White's stones have escaped. <= ]
)
(;B[jd]
C[Failure.  

The diagonal move of Black 1 is also slack. ]
;W[le];B[jf];W[lg]
LB[le:2]
C[After 2 and 4, White's stones are out in the center. ]
)
(;B[ke]
C[Failure.  

Capping is another common attacking technique, but, after Black caps with 1, ... ]
;W[jd]
C[... White escapes ... ]
;B[if];W[je];B[jf];W[hd];B[hc];W[gd];B[gc];W[hf];B[hg];W[gf]
LB[kf:A]
C[... with the sequence to 12. Black has failed to make any significant gains, and White has the cut at A to exploit. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ce][qq][ci][eq][fp]
AB[dc][qd][cp][dm][hp]
C[Problem 17. Black to play.  

Black wants to keep the two white stones on the lower left unsettled. How should he play ? ]
(;B[cq]
TE[2]
C[Correct Answer.  

Descending to Black 1 is a solid move. ]
;W[fn]
C[White has to jump to 2, so ... ]
;B[kp]
C[... Black can take up a position at the bottom by extending to 3. <= ]
)
(;B[dq]
C[Failure.  

Many player would instinctively attach with 1, but ... ]
;W[dr];B[cr];W[dp];B[cq];W[do]
C[... White would make shape with the sequence to 6. ]
;B[cn]
C[Black has to link up with 7, so ... ]
;W[jp]
C[... White will be able to attack the black stone at the bottom with a pincer at 8. <= ]
)
(;B[kp]
C[Failure.  

If Black extends with 1, ... ]
;W[cr]
C[... White can settle her stones by sliding to 2. Black has failed. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cf][df][de][dg][ic][id][ie][qf][pi][ck]
AB[dc][cd][ce][ef][fd][hd][kd][kc][nd][pd][pp][jp][dp]
TR[ic][ie][id]
C[Problem 18. Black to play.  

How should Black attack the three marked stones ? ]
(;B[ig]
TE[2]
C[Correct Answer.  

Black caps with 1. ]
(;W[ge]
C[If White peeps with 2, ... ]
;B[gg]
C[... Black 3 confines the white stones to the top. ]
;W[ec];B[ed];W[dd];B[db];W[cc];B[bc];W[eb];B[cb];W[gc];B[gd];W[hc];B[he];W[jb];B[kb];W[fc]
C[White lives at the top in gote with the sequence to 18, so ... ]
;B[qk]
C[... Black can switch to the right side and attack the two white stones there with 19. <= ]
)
(;W[jf]
C[Variation.  

If White tries to escape with 2, ... ]
;B[kh]
C[... Black keeps her stones confined with the knight's move of 3. ]
;W[lf]
C[If White 4, ]
;B[mh]
LB[pf:A]
C[... Black 5. If White continues to run away, Black can lean on the white stones on the right by attaching at A, so White will suffer a loss on the right or lose her stones at the top. <= ]
))
(;B[jf]
C[Failure.  

The knight's move of Black 1 lacks forcefulness. White ... ]
;W[if];B[jg];W[ig];B[jh];W[hi]
C[... runs away with the sequence to 6, and the wall Black makes is ineffective because of the two white stones on the right. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dj][dp][jp][kd][nc][qg][qf][qd][qc][qb][pb]
AB[id][ob][oc][pc][nd][pd][pe][pg][ph][pj][lp][pp]
TR[kd]
C[Problem 19. Black to play.  

How should Black attack the marked white stone ? ]
(;B[jf]
TE[2]
C[Correct Answer.  

Black should play the knight's move of 1. ]
;W[lf]
C[If White runs away with 2, ... ]
;B[kh]
TR[pj][ph][pg][pe][pd][pc][ob][oc][nd]
C[... Black drives White into his marked stones with 3. White's stones are lost. <= ]
)
(;B[kf]
C[Failure.  

Capping with Black 1 is a terrible move. ]
;W[je]
C[White moves out into the center with the diagonal move of 2. ]
;B[ig]
C[If Black 3, ... ]
;W[ie]
TR[id]
C[... White plays 4 and neutralises the marked stone. Black has suffered a big loss. <= ]
)
)
(;
GM[1]
SZ[19]
AW[fq][dr][cr][cq][cp][cn][jq][jp][lp][ln][jn][jl][kl][mg][lf][mi][lk][mk][po][qp][qm][ql][qk]
AB[dd][dp][do][dq][eq][er][fp][ip][iq][io][lm][ll][kk][kj][kh][pd][og][pj][pk][pl][nl][on][oo][oq]
TR[kk][kj][kh][lf][mg][mi][mk][lk]
C[Problem 20. Black to play.  

Both the black and white marked stones are floating in the center. It is Black's move. What should he do ? ]
(;B[jf]
TE[2]
C[Correct Answer.  

Black should attack with the knight's move of 1. ]
;W[ld]
C[After the exchange of 2 ... ]
;B[jd]
C[... for Black 3, ... ]
;W[nd]
C[... White makes shape with 4. but ... ]
;B[pc]
C[... Black secures the corner and a thick position with 5. White is in trouble. <= ]
)
(;B[ld]
C[Failure.  

Black 1 is in the wrong direction. ]
;W[jf]
C[It induces White to save her stones, while leaving Black's stones seriously injured. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][de][dh][ck][gq][jq][qp][pp][qr][pq][np][qb][oc][nd]
AB[cm][cp][eq][qq][rr][rq][rp][qn][qj][pf][qd][mc][ld][ec][hc]
TR[nd][oc][qb]
C[Problem 21. Black to play.  

The position in the top right arose from a basic joseki. How should Black attack the marked stones ? ]
(;B[pd]
TE[2]
C[Correct Answer.  

Black 1 may seem like a strange move, but it is quite effective. ]
(;W[ob]
C[White 2 is an important defensive point, but ... ]
;B[rc];W[nf];B[me];W[ne];B[ph]
C[... Black secures the right side with the sequence to 7. <= ]
)
(;W[rc]
C[If White tries to get more room in the corner with 2, ]
;B[pb]
C[... Black will attach at 3, then ... ]
;W[pc];B[qc];W[ob];B[rb];W[pa];B[ra]
C[... take the corner for himself with the sequence to 9. ]
;W[nf]
C[White still doesn't have two eyes, so she must escape with 10. ]
;B[me]
C[After 11, ... ]
;W[ne];B[ph]
LB[ob:A]
C[... Black secures the right side with 12. This result is similar to the previous variation (White 2 at A). <= ]
))
(;B[nf]
C[Failure.  

Black 1 is slack. ]
;W[rc];B[rd];W[nb]
LB[me:A]
C[White can secure her stones with the sequence to 4, and Black's territory on the right side is not as secure as it was in the Correct Answer. White is now threatening to keep Black's positions separated by moving into the center with A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ce][cd][cg][cm][dm][dn][do][eq][pq][qn][oc][id][if]
AB[de][ec][ef][eh][cr][cp][co][cn][kq][qd][pe][nd][kd]
TR[if][id]
C[Problem 22. Black to play.  

What should  Black do about the marked stones at the top ? Pay attention to Black's four stones on the left. ]
(;B[ih]
TE[2]
C[Correct Answer.  

Black should cap with 1. ]
;W[kf]
C[If White jumps to 2, ... ]
;B[nc]
TR[ec][de][ef][eh]
C[... Black secures the corner with 3. The important point here is that the marked stones can't be easily attacked after Black 1, while White's stones at the top are still vulnerable. <= ]
)
(;B[kf]
C[Failure.  

Chasing White into the center with Black 1 ... ]
;W[ih];B[kh]
TR[oc][ec][de][ef][eh]
C[... and 3 weakens the marked stones in the upper left. Not only are these stones in trouble, but the marked white stone in the upper right still has aji. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][nq][kq][ko][eq][dp][dn]
AB[pd][pi][oo][qo][pq][iq][fq][fp]
TR[pi]
C[Problem 23. White to play.  

Black has stakes out a moyo on the right side with the marked stone. What should White do ?  

[You will find a supplement to this Problem Diagram as "Problem 138"] ]
;W[io]
TE[2]
C[Correct Answer.  

White should cap with 1. ]
;B[fn]
C[If Black jumps to 2, ... ]
;W[go]
C[... White will peep with 3, ... ]
;B[fo];W[dl]
C[... then jump to 5, staking out territory on the left side. Black's stones are heavy and Black must continue to defend them. <= ]
)
)
(;
GM[1]
SZ[19]
AW[db][dc][ce][nd][pc][qc][qf][pg][pj][pk][pl][mk][qm][rm][rn][qn][ro][rp][qq][qr]
AB[ec][ed][jd][pd][qe][pf][qg][qh][qi][qj][ql][rl][sm][pq][pp][qo][pn][pm][jp][dp]
TR[mk][pj][pk][pl]
C[Problem 24. Black to play.  

White's marked stones are vulnerable, but Black's stones at the top are also thin. What should Black do ? ]
;B[kk]
TR[pl][pj][pk][mk]

TE[2]
C[Correct Answer.  

Black should first go after the marked white stones on the right by capping with 1, ... ]
;W[mi];B[ki]
C[... drive them towards the top with 3 ... ]
;W[mg];B[kg]
C[... and 5. ]
;W[me];B[df]
LB[me:6]
C[After White 6, Black puts pressure on the white stones on the left with 7 ... ]
;W[cf];B[dg]
C[... and 9. ]
;W[cg];B[di];W[dh];B[eh];W[ch];B[ei]
C[With 15, Black ends in gote, but his stones on the top are no longer thin and he has built a moyo in the center. Black has an overwhelming advantage. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cj][dd][dp][dn][hp][iq][hq][jq][lq][qi]
AB[fq][fo][go][ho][ip][jp][kp][mo][pp][pd]
TR[cj]
C[Problem 25. Black to play.  

White has just extended along the left side with the marked stone. What should Black do ?  

[You will find a supplement to this Problem Diagram as "Problem 139"] ]
;B[mr]
TE[2]
C[Correct Answer.  

Black should attack the white stones at the bottom with 1. ]
;W[lr];B[nq];W[gr];B[fr];W[kq]
C[White can live in the sequence to 6, but Black ends in sente, so ... ]
;B[pj]
C[... he can continue by building a moyo in the center by making a shoulder hit at 7. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cj][cm][dp][dq][kq][nq][pp][pd][od][qc][rc]
AB[dc][cf][fq][iq][io][qn][pk][kc][qd][pe][qf][re]
TR[od][pd][qc][rc]
C[Problem 26. Black to play.  

The four marked stones seem to be secure, but Black has a way to uproot them. How should Black attack ? ]
(;B[ob]
LB[pc:A]

TE[2]
C[Correct Answer.  

Black 1 is the vital point. It aims to cut at A. This is a typical example where it is strategically best to gouge out the opponent's base. ]
(;W[pb]
C[White must defend with 2, but ... ]
;B[oc];W[pc];B[mc]
C[... Black makes shape at the top with the sequence to 4. The white stones are left without two eyes, so White must escape into the center. Black can make profit by threatening these stones. <= ]
)
(;W[nc]
TR[ob]
C[Variation.  

Attacking the marked stone with 2 ... ]
;B[nb];W[mc]
C[... and 4 doesn't accomplish much. ]
;B[mb]
LB[nb:3]
C[Black links up his stones with 3 and 5, so ... ]
;W[pc]
C[... White must come back to defend the cut with 5. ]
;B[me]
C[Black can now attack at the vital point of 7. <= ]
)
(;W[oc]
C[Variation.  

White 2 ... ]
;B[nb];W[pb]
C[... and 4 is another way for White to defend, but ... ]
;B[md]
LB[nb:3]
C[... her stones are still under attack after Black 3 and 5. <= ]
))
(;B[nc]
C[Failure.  

Black 1 is a slack move. ]
;W[ob];B[oc];W[pc];B[nb];W[pa]
C[White easily makes life in the corner with the sequence to 6. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][dd][cf][cg][cn][dp][nq][mr][ns][or][pr][qq][qc][qd][qf][rf][jd][ke][jf][lg]
AB[dg][di][fq][lq][mq][np][pp][pn][pc][pd][pe][og][qh][db][fc][ic][id][ie][je]
TR[jd][ke][jf][lg]
C[Problem 27. Black to play.  

White has played lightly with the marked stones. How should Black attack them ? ]
(;B[li]
TE[2]
C[Correct Answer.  

Capping with Black 1 is the best way to attack. ]
;W[jh];B[jj]
C[White will probably live, but, even if she does, Black will build a large moyo below while attacking, and White will get minimum territory. <= ]
)
(;B[kd]
C[Failure.  

If Black cuts at 1, ... ]
;W[ld]
C[... White ataris at 2 and ... ]
;B[kc];W[le];B[lc];W[jh]
C[... makes eye shape with the sequence to 6. White will now have no trouble making a living group in the center and Black has no prospects of making a moyo. <= ]
)
(;B[kf]
TR[jd][ke]
C[Failure.  

Black can capture the two marked stones by cutting at 1, but ... ]
;W[kg];B[lf];W[mf];B[le];W[me]
C[... White can force with the sequence to 6, then ... ]
;B[ld];W[nh]
LB[md:A]
C[... make shape with the knight's move of 8. White should have no trouble getting eyes for her group. It is now her privilege to play at A and Black's three stones at the top are in danger of being cut off. <= ]
)
)
(;
GM[1]
SZ[19]
AW[aa][ca][db][bb][bc][bd][dd][ec][fd][fe][ge][gf][he][hd][hc][hb][ib][lb][md][le][kf][lf][lg][oc][pc][qb][qd][bi][ci][ch][dh][dg][cj][ej][ek][dn][dp][cp][dq][bq][rq][qp][ro][pn][gh][hg][hi][hj][hk][jj]
AB[qc][rc][rb][pd][pe][qg][ic][jb][kb][kc][jd][ie][if][hf][jg][kg][lh][ki][cb][cc][cd][be][de][ef][eg][fg][gg][eh][ei][cf][cg][bg][bh][cq][br][dr][cr][fq][kq][op][pq][qq][gi][gj][gk][gl]
TR[hg][gh][hi][hj][hk][jj]
C[Problem 28. Black to play.  

The marked white stones are floating in the center, but Black's group in the upper left is also without eyes. What should Black do ? ]
(;B[gn]
TE[2]
C[Correct Answer.  

Black 1 is a calm and solid move which ensures that the black stones in the upper left are linked to their allies below. ]
(;W[lk]
C[White's stones must escape into the center. White 2 is reasonable, but ... ]
;B[nh]
C[... it provokes Black 3. ]
;W[lc]
C[White's group at the top does not have eyes, so she defends with 4. ]
;B[jl]
C[Next, Black goes on to attack with 5 ... ]
;W[kj];B[lm]
C[... and 7. The white stones in the center will escape, but Black has made a huge territory at the bottom. <= ]
)
(;W[hl]))
(;B[hl]
C[Failure.  

Black 1 is a forceful move, but it strengthens White's weak group. ]
;W[il];B[im];W[jl];B[jm];W[kl];B[km];W[go]
LB[hm:A][km:7]
C[After 7, White will jump to 8, threatening to cut at A or to invade the bottom. <= ]
)
(;B[lk]
C[Failure.  

Black 1 is an all-out attack, but ... ]
;W[hl];B[gm];W[in];B[go]
C[... White will fight like a trapped animal after Black 5. It is hard to predict what will happen, but, if White survives, Black's territory at the bottom could be wiped out. The sequence in the Correct Answer gives Black a sure win. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][df][qq][nr][nq][mp][no][nn][on][om][ol][nk][ql][lo][dp][go][ip][jp][kp]
AB[fc][kc][qd][qi][pp][oq][or][pn][ro][nm][mm][mn][mo][lp][lq][kq][jq][hq][gq]
TR[lo][mo][mn][mm][nm]
C[Problem 29. Black to play.  

Black's marked stones are in danger, and he can't capture the marked white one because the ladder is unfavourable. What should Black do ? ]
;B[ko]
TE[2]
C[Correct Answer.  

Black should atari with 1, ... ]
;W[ln];B[km]
C[... then cast a net with 3. ]
;W[kn];B[jn];W[jo]
LB[ko:1]
C[White can capture the stone at 1, but ... ]
;B[lm]
C[... she gets squeezed in the sequence to 7. ]
;W[ko]
C[After White 8, ... ]
;B[in]
C[... Black makes good shape with 9 and ends in sente, ... ]
;W[ho]
C[... since White is forced to connect at 10. <= ]
)
)
(;
GM[1]
SZ[19]
AW[fc][fq][qn][qj][md][nc][oc]
AB[dd][dj][cn][dp][pp][nq][pc][pd][nd][ne][pf]
C[Problem 30. Black to play.  

Black's position in the upper right is thick, while White's stones at the top are thin. How should Black attack ? ]
(;B[kd]
TE[2]
C[Correct Answer.  

Black 1 is the vital point in this position. Next ... ]
(;W[me]
C[Pushing up with 2 is only natural, but ... ]
;B[mf]
C[... Black blocks with 3, ... ]
(;W[le]
C[... forcing White to turn with 4. ]
;B[lb]
C[Next, Black peeps with 5 and ... ]
;W[mc]
TR[fc]
C[... White's stones are left heavy and separated from the marked one on the left. White is in trouble. See Problem 136 for the continuation. <= ]
)
(;W[ke]
C[Variation.  

If White attaches at 4, ... ]
;B[le]
C[... Black will wedge in at 5. ]
;W[ld];B[lf];W[kc];B[jd];W[jc];B[id];W[ic];B[hd];W[hc];B[gd]
C[The sequence to 15 is inevitable. White has secured the top, but Black's thickness in the center is strategically overwhelming. <= ]
))
(;W[le]
C[Variation.  

The diagonal move of White 2 is another possibility. ]
;B[lb]
C[Again Black peeps with 3. ]
;W[mc];B[ke]
C[After exchanging 5 ... ]
;W[lf]
C[... for 6, ... ]
;B[lh]
TR[fc]
C[... Black caps with 7. If the fight spreads to the left, the marked stone will be weakened. <= ]
)
(;W[kb]
C[Variation.  

If White slides to 2, ... ]
;B[jc]
C[... Black will force White to run along the second line. ]
;W[jb];B[ic];W[ib];B[hc];W[hb];B[gc];W[gb];B[fd];W[ec];B[ed]
C[After the sequence to 13, Black's wall in the center is superior to White's territory at the top. <= ]
))
(;B[me]
C[Failure.  

Turning at 1 is not a good move ... ]
;W[ld]
C[... because White is able to make territory by running on the fourth line ... ]
;B[le];W[kd];B[ke];W[jd]
TR[fc]
C[... and the marked stone works well in protecting White's left flank. Moreover, the two white stones on the right side neutralises Black's wall. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cc][fc][dp][cn][qq][rr][oq][or][nr][qn][pn][qk]
AB[bd][cf][ci][fq][jp][mr][nq][np][pp][op][qo][ro][qi][pd]
TR[qk][pn][qn]
C[Problem 31. Black to play.  

How can Black use his thickness to attack the marked white stones ? ]
(;B[oj]
TE[2]
C[Correct Answer.  

The knight's moves of Black 1 .. ]
;W[ol];B[mk]
LB[kd:a]
C[... and 3 are severe. White's stones can live, but Black will have built up influence in the center. He can then stake out a moyo by extending to A. <= ]
)
(;B[ok]
C[Failure.  

Capping at 1 is ineffective because Black is not using his thickness below. ]
;W[pj]
C[White breaks through Black's position with 2, and Black is left without a good follow-up move. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cf][ef][gf][qn][rp][qc][qd][qf][nc][md]
AB[dd][fd][di][dp][jp][pp][np][pd][oc][nd][mc][lc][ne]
TR[gf]
C[Problem 32. Black to play.  

White has just played the marked stone. How should Black continue ? ]
(;B[gi]
TR[pd][oc][nd][ne][mc][lc]

TE[2]
C[Correct Answer.  

The marked stones are thick, so Black should jump to 1 and drive the white stones toward that strong position. ]
;W[he];B[hc];W[je];B[ji]
C[White will probably live in gote, but Black is satisfied with the moyo he has staked out at the bottom. <= ]
)
(;B[hd]
C[Failure.  

Black 1 is overly defensive. ]
;W[fi]
TR[di]
C[White will immediately take the initiative and attack the marked stone with 2. With his thick position at the top, Black's territory is overconcentrated. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][df][qq][nr][nq][mp][no][nn][on][om][ol][ql][nk][ln][lo][kn][ko][jo][jp][kp][ip][ho][go][dp]
AB[fc][kc][qd][qi][pp][ro][pn][oq][or][nm][mm][lm][km][jn][in][mn][mo][gq][hq][jq][kq][lq][lp]
TR[go][ho][ip][jp][jo][ko][kp][lo][ln][kn]
C[Problem 33. Black to play.  

How should Black attack the marked white stones ? ]
;B[gm]
TE[2]
C[Correct Answer.  

Black attacks with 1, ... ]
;W[eo]
C[... and White must defend with 2. ]
(;B[dr]
C[Black 3 is now the key move. ]
;W[dl]
LB[el:A]
C[White must defend by playing around 4. I f White neglects to play here, Black A will be severe. ]
;B[lj]
C[Black now switches his attack to the right with 5 ... ]
;W[ni];B[lh]
C[... and 7.  The white stones on the right are in danger and Black is building a moyo in the center. <= ]
)
(;B[el]
LB[eo:2]
C[Failure.  

After White 2, Black 3 looks like a strong move, but ... ]
;W[eq]
C[... White will attack the black stones at the bottom with 4 ... ]
;B[fr];W[er]
LB[jl:B][ir:A]
C[... and 6. White A now threatens to kill them, so Black must defend in gote. White's stones on the left are secure, so she can attack with a peep at B. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][fd][ic][dp][kq][nq][pr][md][nc][oc][of][ng][pg][qf]
AB[cf][ci][qq][pp][pn][qj][pj][pd][pc][pe][nd][ne][pf]
TR[ng][of][pg][qf]
C[Problem 34. Black to play.  

How should Black attack the marked white stones ? ]
;B[oh]
TE[2]
C[Correct Answer.  

Black first peeps with 1, ... ]
;W[og]
(;B[ld]
C[... then attacks the three white stones at the top with the clamp of 3. ]
(;W[me]
C[If White extends to 4, ... ]
;B[mc]
C[... Black cuts at 5. If White ... ]
;W[lc];B[mb];W[lb];B[mf];W[le];B[lf];W[ke]
C[... insists on saving her stones at the top with the sequence to 12, ]
;B[mh]
C[... Black casts a net with 13, ... ]
;W[mg];B[lg];W[nh];B[ni]
C[... trapping the white stones on the right. ]
;W[oi]
C[If White cuts at 18, ... ]
;B[nj]
C[... Black extends at 19 and White's stones can't get two eyes. <= ]
)
(;W[lc]
TR[ld]
C[Variation.  

If White answers the marked stone with 4, ... ]
;B[me]
C[... Black presses along the top with 6 ... ]
;W[mc];B[kd]
C[... and 8. ]
;W[kc];B[mh]
C[He then casts a net with 9, trapping the white stones. <= ]
))
(;B[mf]
C[Failure.  

Black 3 aims at both the white stones at the top and on the right, but it lacks in severity. ]
;W[nh];B[nj];W[lh];B[mc]
C[When Black cuts at 7, ... ]
;W[mb]
C[... White can live at the top with 8 ... ]
;B[lc];W[lb]
C[... and 10. White's stones are now safe. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][de][lc][pb][ob][qh][qk][jq][cr][dr][dq][dp][do][ci][di][dj][ck][cl][em]
AB[ec][gd][jc][qb][pc][pd][qf][qm][qp][oq][br][cq][cp][cn][bn][bl][bk][bj][cj]
LB[lc:E][pb:A][ob:C][pc:B][qb:D]
C[Problem 35. Black to play.  

After White plays the sequence from A to E, her stones at the top are not completely settled. How should Black continue ? ]
;B[oh]
TE[2]
C[Correct Answer.  

Black should cap with 1. ]
;W[le]
C[If White defends her stones at the top by jumping to 2, ... ]
;B[ok]
C[... a second cap at 3 is severe. ]
;W[rf]
C[White attempts to live with 4 ... ]
;B[re];W[rg]
C[... and 6. ]
;B[rj]
C[After Black 7, ... ]
;W[qj];B[rk];W[oi];B[pi];W[ph];B[nh];W[oj];B[nj];W[ni];B[mi];W[pj];B[nk];W[ql];B[rl];W[pm];B[pl];W[mh];B[of];W[mg];B[nf];W[ri]
C[... White lives in gote with the sequence to 28. ]
;B[li]
C[After Black extends to 29, ... ]
;W[je]
C[... White runs away with 30. ]
;B[kc]
C[Black exchanges 31 ... ]
;W[lb]
LB[hc:A]
C[... for 32 to defend against the invasion at A, ... ]
;B[kp]
C[... then maps out a large moyo in the lower right with 33. <= ]
)
)
(;
GM[1]
SZ[19]
AW[bc][ce][df][pq][pj][qh][qf][qe][qd][pe][od][nd][ld]
AB[dc][gd][dh][dp][pd][pc][qc][oc][mb][oe][of][pf][oh]
TR[dc][gd]
C[Problem 36. Black to play.  

Because of the two marked black stones, White's three stones in the top right are in danger. How should Black attack ? ]
(;B[kg]
TE[2]
C[Correct Answer.  

Black attacks on a large scale with 1. ]
;W[jd]
C[If White jumps to 2, ... ]
;B[ie]
TR[dc][gd]
C[... Black plays 3 and, because of the presence of the two marked stones, White's stones will have a hard time living. <= ]
)
(;B[kc]
C[Failure.  

Black is thinking on a small scale when he plays 1 ... ]
;W[kd];B[jc]
C[... and 3 along the third line. ]
;W[kg]
TR[oh][pf][of][oe]
C[When White jumps to 4,  it is Black's four marked stones that are in trouble. <= ]
)
)
(;
GM[1]
SZ[19]
AW[nc][nd][mf][lf][cf][dj][cn][qn][rp]
AB[dd][fd][jd][pd][oc][pf][nf][mg][dp][fp][pp][nq]
C[Problem 37. Black to play.  

White's stones at the top are heavy. How should Black attack them ? ]
(;B[ld]
TE[2]
C[Correct Answer.  

Black 1, threatening to separate the white stones, is the vital point of this position. ]
(;W[ne]
C[If White plays 2, ... ]
;B[ng]
C[... Black will connect at 3. ]
;W[le]
C[White must defend against the cut with 4 and ... ]
;B[jf]
TR[ld]
C[... Black continues the attack with 4. The marked black stone is on the vital point, depriving White of eye shape. <= ]
)
(;W[me]
C[Variation.  

White could draw back to 2. ]
;B[ng]
LB[ql:C][qc:A][hd:B]
C[Again, Black connects at 3. White would like to play A or B, but if she does, her stones at the top could get into trouble. On the other hand, Black is free to attack the white stones in the lower right with a pincer at C. <= ]
))
(;B[ne]
C[Failure.  

Black 1 is not a good move. ]
;W[ld]
C[It provokes White to play on the vital point of 2. White's stones now have more stability. <= ]
)
(;B[lg]
C[Failure.  

Pushing along the top with 1 ... ]
;W[kf];B[kg]
C[... and 3. just makes White strong. ]
;W[jf]
LB[hd:A]
C[Black is now vulnerable at the point A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][df][dj][cp][eq][rp][rq][qq][pq][nq][mq][qn][lc][le][ob][pb][rb][qa]
AB[jp][mp][op][np][pp][qp][qo][ro][pj][fc][jc][jd][qb][qc][pc][rc][pd][pf]
TR[le][lc][ob][pb][qa][rb]
C[Problem 38. Black to play.  

White's marked stones in the top right are without eyes. How should Black attack them ? ]
(;B[mg]
TE[2]
C[Correct Answer.  

Black should attack with 1 ... ]
;W[kf];B[kh]
C[... and 3, thereby mapping out an enormous moyo below. <= ]
)
(;B[jf]
C[Failure.  

Black 1 ... ]
;W[lg];B[jh]
C[... and 3 drive White in the wrong direction. Black's thickness at the bottom is now neutralised and the space here is so big that White will have no trouble living. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][ce][gc][kd][mc][qg][qj][pk][qm][dp]
AB[id][oc][qe][pd][og][oj][nl][ql][oq][qp]
TR[qm]
C[Problem 39. Black to play.  

White attaches with the marked stone in order to rescue her stones under siege. How should Black respond ? ]
(;B[pl]
TE[2]
C[Correct Answer.  

Black should push up with 1 and separate the white stones. ]
(;W[ok]
C[If White 2, ... ]
;B[ol]
C[... Black could play 3 and secure the territory on the lower right side. <= ]
)
(;W[rl]
C[Variation.  

But White could hane with 2, ... ]
;B[rk]
C[... Black will block with 3 and, ... ]
;W[qk]
C[... if White cuts with 4, ... ]
;B[rj]
C[... Black will crawl to 5. This is quite a severe move. ]
(;W[ri]
C[If White 6 here, ... ]
;B[rm]
C[... Black will capture a stone by playing at 7. <= ]
)
(;W[rm]
C[If White connects at 6, ... ]
;B[qi]
C[... Black plays 7. Either way, White's position has collapsed. <= ]
)))
(;B[rm]
C[Failure.  

If Black hanes at 1, ... ]
;W[pl];B[qn];W[pm];B[rk];W[pn];B[po];W[nn]
C[... White will escape into the center with the sequence to 8. <= ]
)
)
(;
GM[1]
SZ[19]
AW[kc][nc][pp][rp][nq][jp][dp][do][dq][eq][er][hq][cf][ci]
AB[cd][dd][ic][pc][qd][pj][qn][on][fq][dr][cr][cq][cp][cn]
TR[kc][nc]
C[Problem 40. Black to play.  

Taking the entire board into account, how should Black attack the marked stones ? ]
(;B[ne]
TE[2]
C[Correct Answer.  

Black 1 is a multi-purpose move. It attacks White's two stones at the top while expanding Black's moyo on the right. ]
;W[ke]
C[White must escape into the center with 2. ]
;B[ie]
C[But Black now jumps to 3, strengthening his position in the upper left and ... ]
;W[kg]
C[... forcing White to run away with 4. ]
;B[dh]
C[Black has sente, so he attacks the left side with 5 ... ]
;W[ch];B[df]
LB[mb:B][ld:A][ne:1]
C[... and 7. Suddenly, a black moyo appears in the upper left. White's problems are still not over: Black can take more profit later by peeping at A or making a placement at B. Black 1 follows the old Chinese go proverb: 'When you want to attack in the west, make noise in the east.' <= ]
)
(;B[kd]
C[Failure.  

Attaching with Black 1 is overly aggressive. ]
;W[ld];B[ke];W[jc];B[id];W[le];B[lf]
C[The sequence to 7 is inevitable. ]
;W[ne]
LB[kf:A][jd:B]
C[When White jumps to 8, her stones are secure and Black's prospects for making a large moyo an the right have been blighted. Moreover, Black must worry about the cut of White A or White pushing at B. <= ]
)
(;B[je]
LB[kd:a]
C[Failure.  

Although not as bad as Black a, Black 1 here is slack. ]
;W[me]
LB[pe:B][ke:A][gc:C]
C[White responds by jumping to 2. Black is left without a good follow-up, but White has a good move at A (which secures her stones) and she is threatening to plaster Black against the left side with B. An invasion at C is also an option for her. <= ]
)
)
(;
GM[1]
SZ[19]
AW[bd][dd][fc][dr][fq][iq][pp][oq][ol][ql][lc][me]
AB[cf][ef][dj][dp][cq][dn][qj][oj][od][qd][jc][kd]
LB[lc:A][kd:B][me:C]
C[Problem 41. Black to play.  

How should Black continue after the sequence to White C ? ]
(;B[nc]
LB[ld:A]

TE[2]
C[Correct Answer.  

Black should first defend the corner with 1, threatening to take the territory at the top by playing at A. ]
;W[ld]
C[White defends at this point with 2. but ... ]
;B[kf]
C[... Black continues the attack with 3 ... ]
;W[mg];B[lh]
C[... and 5. The white stones are in trouble. <= ]
)
(;B[ld]
C[Failure.  

Cutting trough with Black 1 ... ]
;W[md];B[mc]
C[... and 3 is crude. ]
;W[nc];B[mb];W[oc]
LB[lb:A]
C[Note that after White 6, White threatens to capture the two marked stones by playing A. ]
;B[lb]
C[Black can capture one stone with 5 and 7, but ... ]
;W[pd];B[pe];W[pc]
C[... Black's corner in the upper right has been destroyed. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ce][dd][fc][ch][cl][bn][co][dp][fp][iq][ql][nc][nb][pc][qc][rc]
AB[cj][dl][bl][bm][cn][dn][kq][op][qp][qj][pd][qd][rd][nd][od][lc]
TR[ql]
C[Problem 42. Black to play.  

How should Black attack the marked stone ? ]
(;B[ok]
TE[2]
C[Correct Answer.  

The knight's move of Black 1 is a strong attacking move. ]
;W[qo]
C[White makes some breathing room for her stones with 2 ... ]
;B[po];W[qn]
C[... and 4, but ... ]
;B[rp]
LB[po:3]
C[... this just induces Black to secure the corner with 3 and 5. ]
;W[om]
C[When White jumps to 6, ... ]
;B[ml]
C[... Black keeps up the attack with 7, and a moyo in the top right suddenly appears that extends well into the center. The important point of this problem is that by attacking a weak white stone, Black has been able to build his moyo and make his territory at the bottom secure, while White busily tries to rescue her stones. <= ]
)
(;B[qn]
C[Failure.  

If Black plays a checking extension to 1, ... ]
;W[ol]
LB[mq:A]
C[... White can easily escape into the center with 2. Later, White can aim to invade at A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][ce][fd][jd][nc][pl][pn][qn][dp][dn][ck]
AB[pd][pf][pj][qo][pp][np][jp][fq][cf][df][ci][ei]
TR[pl][pn][qn]
C[Problem 43. Black to play.  

How should Black attack the marked white stones in the lower right ? ]
(;B[qk]
TE[2]
C[Correct Answer.  

Black 1 is severe because it attacks White's base. ]
(;W[mm]
C[If White jumps out to 2, ... ]
;B[mo]
LB[qq:B][nk:A]
C[... Black can defend at 3 or attack at A. He need not worry about an invasion at B because White must first secure her stones in the center before she can contemplate such an invasion. <= ]
)
(;W[ql]
C[Variation.  

If White makes a base for her stones with 2, ... ]
;B[nk]
C[... Black can attack at 3 ... ]
;W[mm];B[mo]
C[... and 5. ]
;W[nl]
C[White must exchange 6 ... ]
;B[mk]
LB[lq:D][qq:C][ro:B][rm:A][ph:E]
C[... for 7 to maintain the link to the outside. If White gets into trouble in the center, she can make two eyes by playing at A, but Black B would then become sente and White can no longer invade at C. If White can secure her stones, she can aim to invade at D or E, but Black's strategy will be to try and strengthen these defects while attacking the white stones. <= ]
))
(;B[qj]
LB[qk:@]
C[A solid move.  

Making an iron pillar with Black 1 is a solid move. Its appeal is that it prevents a white counterattack at A or an invasion at B. However, it lacks the attacking force of Black 1 in the Correct Answer (@), and, as such, is a bit passive. <= ]
)
(;B[mm]
C[Failure.  

Attacking with Black 1 doesn't press White hard enough. ]
;W[qj]
C[White can secure her stones ... ]
;B[qi];W[qk];B[pi];W[ro];B[rp];W[rn]
LB[hq:C][lq:B][qq:A]
C[... with the sequence to 8. Black ends in sente, but with so many weak points - at A, B, and C - he won't be able to defend all of them. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cf][ch][ci][oi][pi][qi][rk][qg][jc][ld][md][nc][oc][pb][pe][qe][re][rd]
AB[cd][dd][df][dh][dp][pp][pj][oj][nj][ni][pg][nf][me][hc][he][qb][rc][pc][qd][pd][od][nd]
C[Problem 44. Black to play.  

White's stones at the top right are struggling for life inside Black's sphere of influence. How should Black attack them ? ]
(;B[lb]
TE[2]
C[Correct Answer.  

This is the kind of position in which you want to gauge out the eyes of your opponent's stones. The placement of Black 1 robs the white stones of their base and threatens to cut. White's stones are trapped inside Black's sphere of influence. Next ... ]
(;W[mb]
C[If White defends against the cut with 2, ... ]
;B[kc]
C[... Black links up with 3 ... ]
;W[kd];B[jb]
C[... and 5. White is without eyes, so she must seek life in the center. <= ]
)
(;W[kb]
C[Variation.  

White 2 here is another possibility, but ... ]
;B[nb]
C[... Black takes profit with 3 ... ]
;W[mb];B[ob]
C[... and 5. ]
;W[mc];B[ib]
C[After Black 7, White's group still doesn't have two eyes. <= ]
))
(;B[ib]
C[Failure.  

Black 1 ... ]
;W[jb];B[ob]
C[... and 3 are certainly sente, but ... ]
;W[nb]
C[... so is White 4, ... ]
;B[pa];W[lb]
C[... so White can secure two eyes with 6. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][ec][df][dp][jq][jd][jg]
AB[pq][po][pj][pd][md][fc][fd][gg]
TR[pj]
C[Problem 45. White to play.  

Black has just staked out a position on the right side with the marked stone. What should White do next ?  

[You will find a supplement to this Problem Diagram as "Problem 140"] ]
;W[hd]
TE[2]
C[Correct Answer.  

White 1 is the vital point; it makes the difference between Black being attacked or White. ]
;B[ff]
C[Black must defend with 2, ... ]
;W[dh]
C[... and White stakes out the territory on the left side by jumping to 3. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cd][dc][ec][bf][kd][ld][nc][ne][ql][qn][rp][cn]
AB[df][ed][fd][fc][jc][kc][lc][pd][pf][qj][qq][pp][np][dp]
TR[kd][ld][nc][ne]
C[Problem 46. Black to play.  

How should Black attack the four marked white stones ? ]
(;B[lf]
LB[md:A]

TE[2]
C[Correct Answer.  

Black 1 blocks White's escape route into the center and aims at A. ]
(;W[md]
C[If White defends there, ... ]
;B[ng]
C[... Black continues the attack with 3. <= ]
)
(;W[mf]
C[If White attaches with 2, ... ]
;B[md]
C[... Black hanes at the vital point with 3. ]
;W[mc];B[le];W[me]
LB[md:3]
C[White captures the stone at 3 with 6, but ... ]
;B[je]
C[... Black casts a net with 7, making a thick position facing the left. White's stones are still without eye shape. <= ]
))
(;B[pb]
C[Failure.  

Defending the corner with 1 is passive. ]
;W[kg]
C[White can gingerly jump out into the center with 2. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][ec][cd][bf][bp][cn][ck][nq][pr][ke][kf][md][me][li]
AB[cq][dp][fq][pp][qn][pj][pg][qd][pd][od][nd][mc][lc][kd][je][fc][ed][gd][df][ji]
TR[li][kf][ke][me][md]
C[Problem 47. Black to play.  

How should Black attack the marked white stones ? ]
(;B[mf]
TE[2]
C[Correct Answer.  

White 1 is the vital point, forcing White's stones into a bad shape. ]
(;W[lf]
C[If White 2, ... ]
;B[mg]
C[... Black extends to 3, ... ]
;W[kh]
C[... forcing White to defend with 4. The white stones are heavy and open to an attack. See Problem 131. <= ]
)
(;W[nf]
C[White 2 is an overplay. ]
;B[le]
C[Black separates the white stones with 3 ... ]
;W[ne];B[ld]
C[... and 5. <= ]
))
(;B[kk]
C[Failure.  

Black 1 looks like a severe attacking move, but it gives White the chance to counterattack. ]
;W[og]
LB[mf:A]
C[She first plays a forcing move with 2, preventing Black from destroying her shape with A, ... ]
;B[ph];W[jd]
C[... then cuts with 4. Next, ... ]
;B[jc];W[id];B[ic];W[if]
C[... White makes a wall with 8 ... ]
;B[ie];W[jf]
C[... and 10. ]
;B[he]
C[After Black 11, ... ]
;W[mk]
C[... White jumps to 12 and the two black stones in the center are isolated from their allies. As the Correct Answer of this problem illustrates, an important preliminary to attacking is to force your opponent's stones into a bad shape so that it is hard for her or him to make eyes. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][ec][df][ff][gf][ge][jc][jd][kf][nc][og][oh][ph][po][qp][qq][rr][cp][dp][ep][eq][fp][fo][dj]
AB[fd][fc][hd][id][hf][if][gg][ih][pd][pf][nh][oi][pj][pm][qr][pq][nq][mq][lq][kp][jp][ip][hn][gp][fq][gq][er][dq][cq]
LB[ph:A][oi:B][oh:C][nh:D][og:E]
C[Problem 48. Black to play.  

White has just turned with E. How should Black continue the attack ? ]
;B[nd]
TE[2]
C[Correct Answer.  

Black 1 leans on the white stone at the top, simultaneously attacking the three stones below. This move enables Black to get the advantage either at the top or to put a stone in wait for trapping the three white stones below. ]
(;W[ng]
C[If White turns at 2, ... ]
;B[mc]
C[... Black quells the white stone at the top with 3. White's stones in the upper right part of the board are still without a base. <= ]
)
(;W[md]
C[White might resist with 2, ... ]
;B[ne];W[ng]
C[... then play 4 ... ]
;B[me]
(;W[mg]
C[... and 6, but ... ]
;B[mc]
C[... Black again secures his position at the top with 7. <= ]
)
(;W[mc]
C[If White secures the top with 6, ... ]
;B[mg]
C[... Black traps the white stones on the right ... ]
;W[mh];B[ni];W[mf];B[lg];W[nf];B[lf];W[le];B[ke];W[ld];B[lh]
C[... with the sequence to 17. ]
;W[mi]
C[White can't escape with 18 ... ]
;B[mj]
C[... because the ladder is unfavourable. <= ]
))
)
(;
GM[1]
SZ[19]
AW[dd][fd][kc][nc][pb][ph][qm][qp][oq]
AB[qc][pd][pf][qk][ok][dp][dj][cf]
TR[ph]
C[Problem 49. Black to play.  

The marked white stone has a lot of room to maneuver. How should Black attack ? ]
(;B[oi]
TE[2]
C[Correct Answer.  

The shoulder hit of Black 1 is severe. ]
;W[oh]
C[If White 2, ... ]
;B[nh]
C[... Black presses with 3 and ... ]
;W[og]
C[... White has to turn at 4. ]
;B[nd]
C[Black now leans on White's stones above with 5. ]
(;W[ng]
LB[nd:5]
C[White might want to ignore Black 5 and turn at 6. ]
;B[mc]
C[Black would the play 7 ... ]
(;W[mb];B[md];W[nb]
C[If White defends upon to 10, ... ]
;B[mg];W[mh];B[ni];W[mf];B[lg];W[nf];B[lf]
C[... Black traps White's stones on the right with the sequence to 17. <= ]
)
(;W[lg];B[md]
C[... and 9, taking a large profit at the top. Black is satisfied with this result. <= ]
))
(;W[md]
C[If White defends the top with 6, ... ]
;B[me]
C[... Black keeps up the pressure with 7. ]
(;W[ld]
C[After White 8, ... ]
;B[ng]
C[... Black turns at 9 and the white stones on the right are trapped. <= ]
)
(;W[ne]
C[If White plays at 8 here, ... ]
;B[nf]
C[... Black ataris at 9 here. The white stones on the right are trapped. ]
)))
(;B[nh]
C[Failure.  

Capping with Black 1 doesn't work ... ]
;W[pj]
C[... because White will peep with 2. ]
;B[pk];W[ni];B[oi];W[oh];B[mi];W[ng];B[nj];W[of]
C[White now extricates her stones with the sequence to 10. White's stones are safe, but the three black stones in the upper right corner are in trouble. <= ]
)
(;B[ng]
C[Failure.  

Attacking from above with Black 1 ... ]
;W[nh];B[mh]
C[... and 3 is out of the question. ]
;W[ni];B[mg];W[mi];B[li];W[lj];B[ki];W[mk]
TR[qk][ok]
C[After White 10, the two marked stones are isolated and without a base. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][cd][de][dg][ch][fc][hc][ge][he][ie][je][jd][hg][ih][md][od][pc][qd][rd][rc][oc]
AB[cb][dc][eb][ed][ee][ef][gf][fh][dp][pp][pd][id][ic][jc][kd][ke][jf][kg][le][lf][qc][pe][dk][qb][qe]
LB[rc:A][qb:B][oc:C][qe:D][rd:E]
C[Problem 50. Black to play.  

After the sequence to White E, how should Black attack the white stones at the top center ? ]
;B[ij]
TE[2]
C[Correct Answer.  

Black must cap at 1. ]
(;W[hi]
C[If White 2, ... ]
;B[gh]
LB[ig:A]
C[... Black 3 threatens to cut off the white stones at the top with A, ... ]
;W[ig]
C[... so White must defend there. ]
;B[gk]
C[Black 5 now blocks White's escape route. <= ]
)
(;W[hj]
C[Variation.  

Attaching with 2 is White's best chance to create complications, but ... ]
;B[hi];W[ii];B[hh];W[ig]
(;B[ik];W[gg];B[ei]
C[... Black secures his stones with 9. White must escape. ]
;W[kh]
C[If she attaches with 10, ... ]
;B[oe]
C[... Black plays the sente move of 11 ... ]
;W[rb];B[lh]
C[... and attacks with 13 ... ]
;W[ki];B[mj]
C[... and 15 Black will build a moyo while White escapes. <= ]
)
(;B[ki]
C[Jumping to Black 7 is also a strong move. ]
;W[gg];B[ei];W[jj];B[ik];W[ji];B[oe]
C[Here too, Black exchanges 13 ... ]
;W[rb]
C[... for 14, ... ]
;B[lj]
LB[ij:1]
C[... then starts to map out his moyo with 15, while keeping the white stones under attack. See Problem 135 for another response to the cap of Black 1. <= ]
))
)
(;
GM[1]
SZ[19]
AW[dd][hc][pb][oc][pd][pe][of][qo][qm][eq][fp][jq][mq]
AB[kc][qb][qc][qd][qe][qg][pc][pq][op][pn][cj][cp][do]
C[Problem 51. Black to play.  

The middle game has begun. How should Black attack ? ]
(;B[nc]
TE[2]
C[Correct Answer.  

Black expands his position with 1 ... ]
;W[ob];B[nd]
C[... and 3, leaving White's stones heavy. ]
;W[od];B[lf]
C[He then makes shape with 5, ... ]
;W[oh]
C[... forcing White to escape with 6. ]
;B[qp]
C[Next, Black attaches with 7. White's stones are now unsettled, while Black's are secure. <= ]
)
(;B[qp]
C[Failure.  

If Black immediately attaches with 1, ... ]
;W[mc]
C[... White can make shape by taking the vital point of 2. The black stone at the top is now isolated and weak. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][fc][kc][ld][nc][pb][jl][io][ko][dp][eq][fr][cn][di][pm][qp]
AB[pd][qc][pf][lf][je][pk][ll][kq][ip][hp][fp][fq][gr][op][pq][qq]
TR[pm][qp]
C[Problem 52. Black to play.  

The two marked stones are not very strong, but they still have some aji. How should Black attack them ? ]
(;B[qk]
TE[2]
C[Correct Answer.  

Black 1 forces the white stones to escape ... ]
;W[nm]
C[... with 2, but ... ]
;B[ln]
C[... Black prevents them from linking up with 3 ... ]
;W[no];B[lo]
C[... and 5. ]
;W[oo]
C[White tries to make shape with 6, but ... ]
;B[qn]
C[... Black 7 leaves White's stones eyeless within Black's sphere of influence. <= ]
)
(;B[nl]
C[Failure.  

Black 1 looks like a strong move, which builds a moyo in the center, but ... ]
;W[qk]
C[... this gives White the chance to attach with 2. ]
;B[qj]
C[If Black 3, ... ]
;W[rj]
C[... White hanes with 4 and she will easily be able to make sabaki. <= ]
)
)
(;
GM[1]
SZ[19]
AW[lc][qc][qd][qf][rf][pp][dp][bd][cf][ci]
AB[dd][cc][fd][jd][pc][pd][pe][og][qh][jq]
TR[lc]
C[Black to play.  

White has invaded deep inside Black's moyo with his marked stone. What should Black do ? ]
(;B[jc]
TE[2]
C[Correct Answer.  

Black 1 is a solid move. It secures Black's territory in the top left and prevents White from establishing a base there. ]
;W[le]
C[White is forced to escape into the center, but ... ]
;B[md]
C[... Black peeps with 3, ... ]
;W[ld];B[lg]
C[... then severely attacks by capping with 5. ]
;W[kf];B[jh]
LB[kf:6]
C[In response to White 6 Black exchanges 7 ... ]
;W[if]
C[... for White 8, ... ]
;B[dh]
C[... then switches to the left and forces with 9. ]
;W[ch];B[hh];W[gf];B[he];W[hf]
C[After the sequence to White 14, ... ]
;B[df]
C[... Black attaches with 15 and the white stones are in trouble. <= ]
)
(;B[le]
C[Failure.  

If Black caps with 1, ... ]
;W[jc]
C[... White can make a base for her stones at the top by attaching with 2. ]
;B[ic];W[kd];B[ke];W[id]
C[After the exchange of White 6 ... ]
;B[je]
C[... for Black 7, ... ]
;W[ib];B[hc];W[hb];B[gc];W[kb];B[mb];W[gb];B[fb];W[ja]
TR[ci][cf][bd]
C[... White can easily live with the sequence to 16. Compared to the Correct Answer, Black has failed to get any territory at the top and, with White's marked stones on the left, his thickness is ineffective. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][ec][df][ff][gf][ge][jc][jd][kf][nc][og][oh][ph][mh][mi][ng][po][qp][qq][rr][cp][dp][ep][eq][fp][fo][lp][mp][no][ko][jo]
AB[fc][fd][hd][id][if][hf][gg][ih][pd][nd][mc][pf][oi][pj][nh][ni][pm][cq][dq][er][fq][gq][gp][hn][ip][jp][kp][lq][mq][nq][pq][qr]
LB[nd:A][ng:B][mc:C][mh:D][ni:E][mi:F]
C[Problem 54. Black to play.  

The game in Problem 48 continued with the sequence to White F. What should Black do now ? ]
;B[mj]
TE[2]
C[Correct Answer.  

The hane of Black 1 severely attacks White's stones. ]
(;W[lj]
C[If White 2, ... ]
;B[mg]
C[... Black cuts at 3 and ... ]
;W[mf];B[lg];W[nf];B[lf];W[le];B[li]
C[... captures two stones with the sequence to 9. ]
;W[me]
C[White connects at 10, but her stones at the top are in trouble. <= ]
)
(;W[mg]
C[If White defends against the cut by connecting at 2, ... ]
;B[lj]
C[... Black will extend to 3 and ... ]
;W[ki];B[jk]
C[... White's stones are trapped and eyeless after Black 5. <= ]
)
)
(;
GM[1]
SZ[19]
AW[db][eb][gc][hc][dc][de][ce][qf][of][mf][qi][or][nr][nq][mp][jp][ip][hq][fo][di][fm][dn][cp][dq][eq]
AB[ec][ed][ee][gd][hd][id][oc][qd][qk][ok][oi][pn][pp][pr][oq][hp][gp][fp][fq][ep][hn][hl][fk][dk]
TR[mf][of][qf][qi]
C[Problem 55. Black to play.  

How should Black attack the four marked stones in the upper right ? ]
;B[pg]
TE[2]
C[Correct Answer  

Black should peep with 1, ... ]
;W[pf];B[rh]
C[... then make a placement at 3. ]
(;W[od]
C[White can no longer make two eyes on the right side, so she has to switch to the top and ... ]
;B[pc];W[nc];B[nb];W[mc];B[mb];W[lc]
C[... play the sequence to 10, inducing Black to secure the corner. ]
(;B[fi]
C[Black ends in sente, so he takes the key point of 11 to reach out to his stones above and to start building a moyo in the center. <= ]
)
(;B[nn]
C[Failure.  

The aim of 11 here is to map out a moyo with ... ]
;W[fi];B[lo]
C[... 13 and ... ]
;W[lp];B[jn]
C[... 15, but ... ]
;W[gk]
C[... White attaches at 16 and a sharp exchange ensues. ]
;B[gj];W[gl];B[fj]
(;W[hk]
C[White turns at 20 and Black's moyo becomes thin. <= ]
)
(;W[gh]
C[... White could also play 20 here attacking Black's stones at the top. ]
;B[hk]
C[Black would respond at 21. <= ]
)))
(;W[re]
C[Variation.  

The placement of Black 3 is a flexible move. For example, if White exchanges 4 ... ]
;B[rd]
C[... for 5, ... ]
;W[qh];B[ri]
LB[qg:A][qh:6]
C[... Black can crawl to 7 if White plays 6. Since White has to defend her defect at A, Black will end in sente. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][dd][ce][de][df][fc][kd][og][oi][qi][pn][qn][qo][qp][pp][qq][pr][qs][rr][dq][do][ck][cg]
AB[hc][ie][oc][qd][qg][pl][nl][rm][pq][oq][or][op][oo][po][on][ip][ci][bd][cf][dg][eg][ef]
TR[kd]
C[Problem 56. Black to play.  

How should Black attack the marked white stone at the top ? ]
(;B[nf]
TR[kd]

TE[2]
C[Correct Answer.  

Black 1 aims at both the marked stone and the three white stones on the right side. ]
(;W[ng]
C[If White defends with 2, ... ]
;B[kf]
TR[kd]
C[... Black caps with 3 and the marked stone is trapped. <= ]
)
(;W[kf]
LB[nf:1]
C[Variation.  

In answer to Black 1, White might escape into the center with 2, but ... ]
;B[mh]
TR[qi][oi][og]
C[... the three marked stones are in trouble after Black 3. <= ]
))
(;B[kf]
C[Failure.  

If Black immediately caps with 1, ... ]
;W[nd]
C[... White makes a shoulder hit at the vital point of 2. ]
;B[od];W[ne]
C[After 4, White's stones form a cohesive and resilient group, having a lot of room to maneuver. It will be hard for Black to find an effective attack against them. <= ]
)
(;B[md]
C[Failure.  

Black 1 is completely unconvincing. ]
;W[kf]
C[White jumps down into the center with 2, and Black doesn't have a good follow-up. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cf][kc][qc][qd][qf][rf][kq][dp][cq][fq]
AB[fc][id][pc][pd][pe][og][qh][pp][bp][cn][ck]
TR[kc]
C[Problem 57. Black to play.  

White has just invaded with the marked stone. How should Black respond ? ]
(;B[jc]
TE[2]
C[Correct Answer.  

Denying your opponent's stones a base makes attacking easy. Black 1 here ... ]
(;W[ke]
C[... forces White to escape with 2, so ... ]
;B[jf]
C[... Black can continue the chase with 3. ]
;W[ne]
C[White 4 ... ]
;B[pf]
C[... forces Black to defend with 5, but, ... ]
;W[lg]
C[... after White 6, ... ]
;B[li]
C[... Black caps with 7 and White's stones are under siege. See Problem 134 for the continuation. <= ]
)
(;W[kd]
C[Variation.  

White 2 leaves the white stones heavy. With Black's wall on the right, White has no room to develop her stones. ]
;B[jf]
C[The knight's move of Black 3 is now a strong attack. ]
;W[kf];B[kg];W[lf]
LB[lg:A]
C[White 6 at A is also possible. For this variation, see Problem 133. ]
;B[lg];W[ne];B[pf];W[mg];B[mh];W[ng];B[nh];W[nc];B[ob]
LB[lp:B][qb:A]
C[After the sequence to Black 15, the white stones on the top are under attack and Black is threatening the white corner with a hane at A, In addition, Black has made a wall on the outside from which he can now map out a huge moyo with a shoulder hit at B. <= ]
))
(;B[ke]
C[Failure.  

The cap of Black 1 is ineffective. ]
;W[ib]
C[White slides to 2 and ... ]
;B[hc];W[hb];B[gb];W[gd];B[gc];W[mc]
C[... easily lives at the top with the sequence to 8. <= ]
)
)
(;
GM[1]
SZ[19]
AW[gc][hc][fd][ed][dd][cd][be][oc][pd][qj][dj][el]
AB[bd][bc][cc][dc][ec][fc][jc][mc][pp][cp][eq][cl]
C[Problem 58. White to play.  

How should White attack the two black stones at the top ? ]
;W[me]
TE[2]
C[Correct Answer.  

White should cap with 1, then, ... ]
;B[je]
C[... after Black jumps to 2, ... ]
;W[kd]
C[... peep with 3. ]
;B[kc]
(;W[jd]
C[White can cut through with 5 ... ]
;B[id];W[ic]
C[... and 7. ]
;B[ld]
C[If Black breaks through into the center with 8, ... ]
;W[ke];B[le];W[kf];B[lf]
LB[le:10]
C[... 10, and 12, ... ]
;W[kg]
C[... White gets a large moyo when she extends to 13. <= ]
)
(;W[he]
C[Failure.  

If White jumps to 5, ... ]
;B[ld]
C[... Black will reinforce with 6. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ed][dg][dp][oq][ra][rb][qc][pc][oc][nc][pd][mb][na][oe][nf][pf][pg]
AB[cd][hd][po][qp][lb][mc][md][nd][od][pe][qe][qd][qf][rc][sb][sd][rh]
TR[ra]
C[Problem 59. Black to play.  

White has just secured the corner with the marked stone. What should Black do now ? ]
(;B[pi]
TR[nf][oe][pf][pg]

TE[2]
C[Correct Answer.  

Attacking the marked stones with Black 1 is severe. With this move, Black maps out territory on the right side. ]
;W[lf]
C[White must escape with 2, but ... ]
;B[kd]
C[... this induces Black to fix up his shape on the top with 3. White's stones are still without a base. <= ]
)
(;B[lf]
C[Failure.  

Black 1 is the wrong direction. ]
;W[pi]
C[White forces Black ... ]
;B[qj];W[pj];B[qk];W[pk];B[ql]
C[... to crawl along the third line up to 7. ]
;W[li]
C[She then jumps to 8 in good style. Black's position at the top is still defective. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][eq][oc][qp][pq][np][nm][pl]
AB[cp][pc][qd][od][ld][on][po][qo]
TR[nm]
C[Problem 60. Black to play.  

White has just played the marked stone, trying to trap the three black stones. How can Black escape and turn the tables on White, putting her under attack instead ? ]
(;B[mo]
TE[2]
C[Correct Answer.  

The knight's move of Black 1 is the key move. It attacks White's position at the bottom, so White must defend. Next ... ]
(;W[mp];B[lo];W[lp];B[ko];W[jq]
C[... White secures the territory at the bottom with the sequence to 6. ]
;B[pi]
C[Black has sente, so he can turn his attention to the right side and attack White's two stones there with 6. Black's moyo on the right side is bigger than White's territory at the bottom, so this is a good result for Black. <= ]
)
(;W[no]
C[Variation.  

If White plays 2 here, ... ]
;B[nn]
C[... Black can break through White's net with the sequence Black 3, ... ]
;W[mn]
C[... White 4, ... ]
;B[om]
C[... Black 5. <= ]
))
(;B[nn]
C[Failure.  

Pushing from behind with Black 1 ... ]
;W[mm];B[mn];W[lm];B[ln]
C[... to 5 is bad style. ]
;W[lp]
C[White defends the bottom with 6 and Black's stones are heavy and will have a hard time securing themselves. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ce][ed][fd][gd][he][hf][if][jf][pp][qo][mq][oc][pc][mc]
AB[dc][ec][fc][hc][hd][ie][je][ke][kf][dp][fq][qj][qc][qd][pd][od]
TR[hc][hd][ie][je][ke][kf][mc][oc][pc]
C[Problem 61. Black to play.  

Black's marked stones are thick, so the marked white ones are in trouble. Where should Black start his attack ? ]
(;B[lb]
TE[2]
C[Correct Answer.  

Black 1 on the second line is the vital point because it threatens White's base. Moreover, because the black stones are thick, White cannot easily escape into the center. ]
(;W[nd]
C[If White bulges out with 2, ... ]
;B[ne]
C[... Black keeps the white stones confined with 3 ... ]
;W[me];B[mf]
C[... and 5. ]
;W[qb];B[rb];W[nf];B[oe];W[mb];B[le];W[kc];B[lc];W[ld]
C[The sequence continues to 14, but ... ]
;B[md]
C[... Black starts a ko with 15. White has no ko threats, so Black will capture all of White's stones. <= ]
)
(;W[lc]
C[Variation.  

If White 2 here, ... ]
;B[kb]
C[... Black will extend to 3. <= ]
))
(;B[kc]
C[Failure.  

Black 1 is slack. ]
;W[qb]
C[After exchanging 2 ... ]
;B[rb]
C[... for 3, ... ]
;W[nd]
LB[nf:B][lb:A]
C[... White plays 4. A and B are now miai.  

 

 

- if Black A, White escapes with B; if Black B, White makes two eyes with A. <= ]
(;B[lb]
C[If Black 5 here, ... ]
;W[nf]
C[... White escapes with 6. <= ]
)
(;B[nd]
C[Failure.  

Black 1 is a vital point, but, ... ]
;W[qb]
C[... after exchanging 2 ... ]
;B[rb]
C[... for 3, ... ]
;W[lb]
C[... White plays 4 and gets two eyes. ]
(;B[jb]
C[That is, if Black 5 here, ... ]
;W[qa]
C[... White defends at 6. ]
)
(;B[pb]
TR[qb]
C[If Black capture the marked stone with 5, ... ]
;W[ob]
C[... White ataris once, ... ]
;B[qa];W[jb]
C[... then jumps to 8. <= ]
))
(;B[nf]
C[If Black 5 here, ... ]
;W[lb]
C[... White makes two eyes with 6. <= ]
))
)
(;
GM[1]
SZ[19]
AW[dc][ce][gc][mc][qg][qj][dp]
AB[id][oc][pd][qe][ql][qp][oq]
TR[gc]
C[Problem 62. Black to play.  

White has just played the marked stone. How should Black attack the lone white stone at the top right ? ]
(;B[ld]
TE[2]
C[Correct Answer.  

The shoulder hit of Black 1 is a powerful move. ]
;W[md]
C[If White tries to escape into the center with 2, ... ]
;B[me]
C[... Black blocks with 3. ]
;W[ne];B[le];W[nd];B[nf]
C[After Black 7, the white stones are trapped. <= ]
)
(;B[og]
C[Failure.  

If Black attacks the two white stones on the right with 1, ... ]
;W[kd]
C[... White will extend to 2. Now it is Black who has to escape. ]
;B[if]
C[If he jumps to 3, ... ]
;W[kf]
C[... White will follow him with 4. White is becoming strong at the top, while her two stones on the right are quite resilient. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][cd][ce][fc][kc][nc][pb][qj][pl][qn][rp][dp][cq][cn]
AB[pd][qc][qf][qq][pp][np][cl][dj][cf][df][de][iq][fq][dr]
TR[pl]
C[Problem 63. Black to play.  

White has just defended her position on the lower right side. Where should Black play next ? ]
(;B[cr]
TE[2]
C[Correct Answer.  

Most of White's stones are secure, but, if Black crawls to 1, he threatens White's three stones in the lower left corner. Next ... ]
(;W[fp]
C[... White attaches at 2 and ... ]
;B[gp];W[fo];B[go];W[fm];B[gn];W[fn]
C[... secures her stones with the sequence to 7. White has gained no territory, but, ... ]
;B[hl]
C[... when Black plays 8, a large moyo at the bottom is starting to take shape. <= ]
)
(;W[br]
C[Failure for White.  

White 2 here ... ]
;B[bp]
C[... would be answered by Black 3, leaving White without eyes. <= ]
))
(;B[ge]
C[Failure.  

If Black jumps to 1, ... ]
;W[cr]
LB[kq:A]
C[... White will defend with 2. White is strong on the lower left and right, so she can now aim at the invasion of A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][fm][en][dn][co][cp][bq][gp][qn][qk][nc][kc]
AB[cf][di][dl][cq][dp][eo][fo][eq][pq][qp][qi][qf][pd]
TR[cf]
C[Problem 64. White to play.  

Black has just played the marked stone. How should White respond ? ]
(;W[cr]
TE[2]
C[Correct Answer.  

The atari of White 1 robs the black stones of their base. ]
;B[go]
C[Black has to run away ... ]
;W[ip];B[ho]
LB[go:2]
C[... with 2 and 4, but ... ]
;W[lq]
LB[ip:3]
C[... these moves provoke 3 and 5, enabling White to establish a position at the bottom. <= ]
)
(;W[fd]
TR[cf]
C[Failure.  

In the game, White answered the marked stone with 1. ]
;B[cr]
C[Black descended to 2, securing his stones in the lower left. Black has a good game because all of his stones are secure. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cf][dj][dp][cp][gq][qn][qk][ok]
AB[kq][qp][op][oi][qi][pd][nc][id][fc]
TR[ok]
C[Problem 65. Black to play.  

White has just jumped into the center with the marked stone. How should Black attack ? ]
(;B[on]
TE[2]
C[Correct Answer.  

Black should jump to 1. ]
;W[mk];B[mi];W[kk]
LB[mk:2]
C[This drives White into the center with 2 and 4, but ... ]
;B[ki]
LB[rm:C][pk:B][pl:A][mi:3]
C[... Black can follow with 3 and 5 to map out a huge moyo in the upper right sector of the board. Later, Black can take some territory on the right side with the sequence Black A, White B, Black C. <= ]
)
(;B[mj]
C[Failure.  

Attacking with the knight's move of 1 is in the wrong direction. ]
;W[on]
C[White secures her stones with 2 and Black no longer has a vulnerable target. In the Correct Answer, Black naturally builds a moyo, while keeping White under pressure. White 2 also weakens the black stones below. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cd][dc][gc][di][fi][pq][mq][pk]
AB[ce][fe][dm][dp][qo][no][pd][pg]
TR[cd]
C[Problem 66. Black to play.  

White has attached with the marked stone, hoping to put the two black stones under siege. How should Black counterattack ? ]
(;B[ed]
TE[2]
C[Correct Answer.  

Black should play the forcing moves of 1 ... ]
;W[ec];B[bd];W[bc];B[he]
C[... to 5. ]
;W[id]
C[After White 6, ... ]
;B[hi]
C[... Black caps with 7 and the two white stones on the left side are under attack. <= ]
)
(;B[de]
C[Failure.  

Answering the attachment of the marked stone by standing at 1 here leaves the black stones heavy. ]
;W[ed]
C[White peeps with 2 and ... ]
;B[ee];W[hd];B[hg];W[hi];B[he];W[jd]
C[... the black stones are under attack after White 8. <= ]
)
)
(;
GM[1]
SZ[19]
AW[qf][pf][of][nf][pi][qi][rn][pn][po][pp][op][oq][nq][os][ms][jr][jq][jp][jo][im][cp][dp][ci][bc][cd][dd][dc][df][no][mn]
AB[bb][cb][cc][db][fc][jd][nd][pd][qe][og][oi][oj][qj][qk][rm][cn][ck][kn][ko][kq][lp][mp][mq][np][mo][oo][on][om][pq][qq][rp][ro]
C[Problem 67. White to play.  

What should White do in this position ? ]
;W[en]
TE[2]
C[Correct Answer.  

White 1 attacks the two black stones on the left, while mapping out a moyo at the bottom left. ]
;B[ek];W[hc]
C[White next probes at 3, ... ]
;B[jc];W[ng]
C[... then reinforcing her stones on the right with 5. ]
;B[rf];W[rg];B[re];W[dl]
C[Endgame.  

Later, White can play a big endgame sequence with 9 ... ]
;B[dk];W[bm]
C[... and 11. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dp][dn][qc][rd][ob][qf][pf][pg][ph][ng][qi][qj][oj]
AB[fp][mq][pp][ql][kc][pd][nd][qe][re][rf][qg][qh][oi][pi]
C[Problem 68. Black to play.  

How should Black attack the white stones on the right ? ]
(;B[nj]
TE[2]
C[Correct Answer.  

Black 1 ... ]
;W[pj]
C[... forces White to connect at 2. ]
;B[mi]
LB[ol:A][lg:B]
C[Black then plays 3 and the points A and B are miai. Whichever way White plays, she will lose some stones. <= ]
)
(;B[ni]
C[Correct Answer.  

Extending to Black 1 is the standard way to attack. ]
;W[pj]
C[After White defends with 2, ... ]
;B[ol]
C[... Black jumps to 3. Again, White is split into two groups; if she tries to save the one on the right side, her group above will die. <= ]
)
(;B[mi]
C[Failure.  

Black 1 is bad. ]
;W[pl]
C[White can now exchange 2 ... ]
;B[qm]
C[... for 3, ... ]
;W[ni]
C[... then wedge in at 4. ]
(;B[nj]
C[If Black ataris with 5, ... ]
;W[nh]
C[... White extends to 6, and, ... ]
;B[pj];W[ok]
C[... after White 8, the three black stones are trapped. <= ]
)
(;B[nh]
C[Black might atari from above with 5. ]
;W[nj];B[oh]
C[After Black connects at 7, ... ]
;W[oe]
C[... White peeps at 8, ... ]
;B[od];W[mh]
C[... then blocks with 10 and ... ]
;B[mg];W[lh];B[og];W[nf]
C[... the black stones are trapped. <= ]
))
)
(;
GM[1]
SZ[19]
AW[cc][ed][jc][qi][oi][po][qn][pm][fp][cq][cl]
AB[lc][oc][qd][qg][qo][qp][pq][nq][cj][ce][dg]
LB[je:A]
TR[fp]
C[Problem 69. Black to play.  

White has just played the marked stone, but playing at A would have been better What should Black do ? ]
;B[gc]
TE[2]
C[Correct Answer.  

Black 1 is the point to invade. ]
;W[fc]
C[White has to defend her corner with 2. ]
;B[gd]
C[After Black 3, ... ]
;W[ef]
C[... White defends with 4, but this move has little effect on the black stones on the left. ]
;B[je]
C[Black now caps with 5. ]
;W[kd]
C[If White runs away with 6, ... ]
;B[lf]
C[... Black traps the white stone with 7. ]
;W[mc]
C[White 8 is a tesuji-like move, but, ... ]
(;B[mb]
C[if Black calmly links up underneath with 9, ... ]
;W[ld];B[kb]
C[... then defends with 11, White's stones are still trapped. <= ]
)
(;B[md]
LB[mc:8]
C[Failure.  

If Black aggressively counters White 8 by blocking on the outside with 9, ... ]
;W[ld];B[mb];W[me];B[nc];W[kf]
LB[nc:13]
C[... White 14 becomes an effective tesuji after Black captures with 13. Black can't keep White confined. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][fc][hc][dh][dm][dp][po]
AB[he][fe][de][dk][pq][pl][pd]
LB[dk:A][dm:B]
C[Problem 70.  Black to play.  

The exchange of Black A for White B has taken place on the left. How should Black continue ? ]
(;B[cc]
TE[2]
C[Correct Answer.  

Black should attach with 1, ... ]
;W[cb];B[dd]
C[... then reinforce his position by forcing with 3. ]
;W[ec]
C[White must answer with 4. ]
;B[ei]
C[Black can now use his thick position above to attack the white stone with 5. ]
)
(;B[ei]
LB[ec:D][dd:C][cb:B][cc:A]
C[Failure.  

If Black attacks at 1 without reinforcing as in the Correct Answer (A and C), ... ]
;W[ce]
C[... White can attach and cut with 2 ... ]
;B[cf];W[df]
C[... and 4, then ... ]
(;B[cd];W[ee];B[be];W[ef]
C[... link up with the sequence to 8. <= ]
)
(;B[fh]
C[Failure.  

Simply capping with 1 and ... ]
;W[ei]
(;B[gj]
C[... playing the knight's move of 3 just enables White to get the initiative on the left side ... ]
;W[ek]
LB[ei:2]
C[... with 2 and 4. The black stone on the left side still has some aji, but Black is now at a serious disadvantage there. ]
)
(;B[fk]
LB[ei:2][fh:1]
C[After exchanging 1 for White 2, Black could jump to 3. ]
;W[fi];B[gi];W[gh];B[gj];W[fg];B[hh];W[gg];B[hg]
C[Black confines White to the left side with the sequence to 11. This is a reasonable result, but not as good as the one in the Correct Answer. <= ]
))
(;B[ef]
TR[df]
C[Variation.  

When White cuts with the marked stone, Black can't get a good result with the atari of 5 here. ]
;W[dg];B[cd];W[be];B[dd];W[di];B[ej];W[bd];B[cc]
LB[jd:B][db:A]
C[After the sequence to Black 13, White's stones on the left are alive and she can secure her stones at the top by playing A or B. <= ]
))
)
(;
GM[1]
SZ[19]
AW[fc][gd][ge][fe][cn][en][bp][pp][qj][pd][pf]
AB[dd][ed][ec][fd][df][dk][dp][cq][fq][nc][kd]
TR[qj]
C[Problem 71. Black to play.  

White has just played a big point on the right side with the marked stone. Where should Black attack ?  

[You will find a supplement to this Problem Diagram as "Problem 141"] ]
;B[dm]
TE[2]
C[Correct Answer.  

Black should destroy the shape of White's stones by peeping with 1, ... ]
;W[dn];B[cm]
C[... then blocking with 3. Besides making the white stones heavy, Black has reinforced his position on the left. If White again plays elsewhere ... ]
;W[nq]
C[Suppose that White reinforces her position in the lower right with 4. ]
;B[bn];W[bo];B[bm]
LB[bn:5]
C[Black will hane and connect with 5 and 7. ]
;W[bq]
C[If White crawls to 8, ... ]
;B[iq]
LB[co:A]
C[... Black will strengthen his position by extending to 9 and wait for a chance to cut at A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][dc][cd][ce][cg][rc][qc][pc][nc][nb][md][oi][ok][pp][qq][jq][dp]
AB[df][de][dd][ec][fd][lc][nd][od][pd][qd][rd][qk][pm][qo][qp][pq][oq]
TR[md]
C[Problem 72. Black to play.  

White has just played the marked stone. What should Black do ? ]
(;B[nh]
TE[2]
C[Correct Answer.  

Black should make a shoulder hit against the white stone on the right side. ]
(;W[ld]
C[If White follows up at the top with 2, ... ]
;B[mj]
C[... Black attacks with 3 ... ]
;W[om];B[ml]
C[... and 5. ]
;W[qj]
C[After the exchange of White 6 ... ]
;B[ql]
C[... for Black 7, White will have a hard time making life for her stones. <= ]
)
(;W[lj]
LB[nh:1]
C[Variation.  

If White responds to Black 1 by jumping to 2, ... ]
;B[mc]
C[... Black will cut at 3. ]
;W[me];B[jd]
TR[me][md]
C[Next, Black extends to 5, taking the territory at the top and leaving White's marked stones isolated from their allies below. <= ]
))
(;B[mc]
C[Failure.  

Immediately cutting with Black 1 is not good. ]
;W[me];B[jd];W[of];B[qh];W[jf]
C[White turns her stones in the center into a cohesive force with the sequence to 6. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ec][dc][cd][cf][cg][qc][oc][re][qp][pq][np][on][om][pn][qn][rn][pl][nl][ml][mm][lj]
AB[df][dg][dh][ed][fc][gd][mc][ne][pe][ep][jp][po][qo][rm][qm][pm][ol][ok][pk][nk][nm]
C[Problem 73. Black to play.  

All of White's groups are safe. What should Black do ? ]
(;B[kg]
TE[2]
C[Correct Answer.  

Since there is nothing to attack, now is a good time for Black to reinforce his moyo at the top with 1. Black can expect a large territory here. <= ]
)
(;B[mk]
C[Failure.  

In the game, Black cut trough with 1 ... ]
;W[lk];B[ll]
C[... and 3, hoping to isolate the white stones in the center and attack them. ]
;W[kl];B[lm];W[mn];B[km]
C[But the black stones became heavy and vulnerable. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][pp][kp][ho][eq][en][em][dl][ek][fl][fj][fi][dj]
AB[oc][qd][ip][io][in][cp][eh][ei][ej][dk][ck][cl][cm][dm]
C[Problem 74. White to play.  

The three black stones at the bottom are heavy. How should White attack ? ]
;W[kn]
TE[2]
C[Correct Answer.  

White 1 forces Black to run away ... ]
;B[jm]
LB[il:A]
C[... with 2 or A. ]
;W[ll]
C[White keeps up the pressure with 2 and ... ]
;B[jk]
C[... Black must jump to 4. ]
;W[ji]
C[By exchanging 5 ... ]
;B[kj]
C[... for 6, ... ]
;W[mj]
LB[qi:B]
C[... White 7 becomes sente. White can now play at B and build a moyo in the lower right sector of the board. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cd][ic][nc][nd][ne][ng][ph][li]
AB[ie][le][lc][oc][pd][pf][re][dp][pp]
TR[ic]
C[Problem 75. Black to play.  

How should Black attack the marked white stone at the top ? ]
;B[hc]
TE[2]
C[Correct Answer.  

Black's three stones are thin, so he should strengthen them by attacking the white stone at the top. ]
(;W[hb];B[hd];W[gb];B[ed];W[fc];B[fd];W[dc]
C[The sequence to 8 is the best both sides can hope for. ]
;B[df]
C[Finally, Black plays 9 and he has built a wall that will later be effective in attacking the six white stones in the top right. Next ... ]
;W[pn]
C[The game continued with White mapping out a moyo on the right side with 10 ... ]
;B[np];W[nn]
C[... and 12. ]
;B[lp];W[cn];B[dk];W[fq];B[dn];W[cq];B[co];W[dq];B[bn];W[bf]
C[After the joseki in the lower left corner, White slides to 22 to prevent Black from making territory on the left side. See Problem 130. <= ]
)
(;W[hd]
C[Variation.  

If White hanes on the outside with 2, ... ]
;B[id]
C[... Black cuts with 3. White's stones are too week to fight and ... ]
;W[gc];B[hb];W[ib];B[gb]
C[... her position collapses after Black 7. <= ]
)
(;W[id]
C[Variation.  

White might play 2 here ... ]
;B[hd];W[je]
C[... and 4, but ... ]
;B[jd]
C[... Black cuts with 5. ]
(;W[kd]
C[If White sacrifices two stones by playing 6 ... ]
;B[jc];W[kc]
C[... and 8, ... ]
;B[ib]
LB[kb:B][ke:A]
C[... Black captures with 9 and dominates the top. Next, the points A and B are miai. <= ]
)
(;W[hb]
LB[jd:5]
C[If Black cuts at 5, White can't hane at 6. ]
;B[ib];W[jc];B[jb];W[kd];B[kc];W[jd];B[jf];W[if];B[he];W[kf];B[jg];W[ke];B[kg]
C[Black squeezes with the sequence to 19, then ... ]
;W[lf];B[fc]
C[... settles his stones at the top by jumping to 21. <= ]
))
)
(;
GM[1]
SZ[19]
AW[cb][dc][ec][hc][ph][qq][qp][qn][rn][dq][co][eo][bl][bk][ck][ci][di][ei][fn][gn][hp][iq][jq]
AB[bc][cc][dd][ce][fe][oc][qd][ql][om][po][pp][pq][cl][dj][ej][fj][el][en][hl][in][jp][kp][kq]
TR[ph]
C[Problem 76. Black to play.  

White enters Black's sphere of influence with the marked white stone. How should Black attack ? ]
(;B[oi]
TE[2]
C[Correct Answer.  

The shoulder hit of Black 1 not only attacks the invading white stone, it also maps out a  large moyo. ]
(;W[oh]
C[If White pushes out with 2 ... ]
;B[nh];W[ng]
C[... and 4, ... ]
;B[mg]
LB[mh:A][nh:3]
C[... the two-step hane of Black 3 and 5 is severe. Simply extending to A with 5 is also good, and this move avoids complications. <= ]
)
(;W[qe]
C[Continuation.  

In the game, White forced with 2 ... ]
;B[pd];W[pi]
C[... and 4, ... ]
;B[pj];W[of]
C[... then jumped to 6. ]
;B[re]
C[Black made his corner thick with 7, then ... ]
;W[mf];B[lh]
C[... followed it up by mapping out a large moyo with 9 ... ]
;W[kf];B[jg]
C[... and 10. Note that White's moves have gained her no territory, while each of Black's have expanded either his moyo or secured the corner. <= ]
))
(;B[og]
TR[ph]
C[Failure.  

Attacking the marked stone with the shoulder hit of 1 is the wrong direction. ]
;W[oh];B[nh];W[oj]
C[Black gains no territory with these moves and he drives the white stones into his potential moyo. It is unreasonable to expect to kill the white stones in such an open space, especially since Black's stones in the lower right are thin. <= ]
)
(;B[nh]
C[Failure.  

Although capping is a good way to attack in many positions, Black 1 is bad. ]
;W[oi];B[ni];W[ok]
LB[nj:B][pl:A][oi:2]
C[The result after White 2 and 4 is similar to the preceding diagram. White is now aiming at A, so Black must defend. Therefore, White will be able to play on the vital point of B. ]
)
)
(;
GM[1]
SZ[19]
AW[dd][jc][ri][qj][pj][pi][ni][ok][dp][fq][iq][jq][kq][mq][mp]
AB[pd][pg][ng][qh][pk][qk][qm][pq][op][mo][no][lp][kp][jp][ho]
TR[ho][jp][kp][lp][mo][no][ni][ok][pj][pi]
TR[qj][ri]
C[Problem 77. Black to play.  

Note the thick black wall (the marked stones) at the bottom. How should Black attack the marked white ones ? ]
(;B[lh]
TE[2]
C[Correct Answer.  

Black drives White into his thick wall at the bottom with the knight's moves of 1 ... ]
;W[lj];B[ji]
C[... and 3. ]
;W[ol];B[pm];W[jk]
C[After 6, White can probably live, but Black gets influence in the center, giving him a huge advantage at the top. ]
;B[hc]
C[Black now uses his advantage by invading at 7. ]
;W[je];B[he];W[mc]
C[White extends to 10, but ... ]
;B[nb]
C[... Black plays the vital point of 11, ... ]
;W[jg];B[if]
C[... then confines the white stones at the top with 13 ... ]
;W[jf];B[ih]
LB[df:A]
C[... and 15. White will live in gote, but, in the process, Black will be able to strengthen his corner. With this sente, Black will next play A. <= ]
)
(;B[li]
C[Failure.  

The cap of Black 1 drives the white stones in the wrong direction. ]
;W[mh];B[kg];W[mg]
C[After 4, White's stones should have no trouble making two eyes. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cj][ek][fj][fl][fm][cl][cn][dn][dp][eq][lj][kk][kl][jl][im][in][hn][ip][nc][pb][qc]
AB[fq][fp][el][em][en][fn][gn][gm][hm][hl][il][ij][jk][kj][ki][mp][pq][pk][pd][pf][lc][le]
TR[ip][in][hn][im][jl][kl][kk][lj]
C[Problem 78. Black to play.  

How should Black attack the marked white stones ? ]
(;B[kn]
TE[2]
C[Correct Answer.  

Black should peep at 1 to destroy White's eye shape. ]
;W[km];B[mn];W[ml];B[li];W[mj];B[nk]
C[After Black 7, White's stones have barely one eye, while Black is threatening to make a moyo in the lower right. <= ]
)
(;B[lk]
C[Failure.  

Cutting with 1 ... ]
;W[kn]
C[... lets White make an eye with 2. ]
;B[mk];W[qo]
C[Since her stones are now relatively secure, she can invade Black's sphere of influence in the lower right with 4. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][fc][qf][pi][ej][gj][ck][dm][dn][cp][dq][cr][lo][ln][qo][mp][mq][lq][mr][fq][hq][gp][gq][gr][iq][ip]
AB[jd][pd][rf][re][dr][eq][fr][ep][fp][em][el][go][ho][hp][io][ko][kp][lp][mo][no][np][po][pm][qp][pq]
TR[pi][qf]
C[Problem 79. Black to play.  

How should Black attack the marked white stones ? ]
(;B[ni]
TE[2]
C[Correct Answer.  

Capping with Black 1 is best. ]
(;W[qk]
C[If White defends with 2, ... ]
;B[og]
C[... Black plays 3 and a moyo begins to appear at the top. <= ]
)
(;W[og]
C[If White 2 here, ... ]
;B[qk]
C[... Black plays 3 here and White's stones will come under attack. <= ]
))
(;B[qg]
C[Failure.  

Black 1 has no strategic significance. ]
;W[pg];B[qh];W[ni]
C[White lightly jumps to 4 and Black no longer has an attack. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][bq][cp][bo][dm][gq][hq][hp][io][jo][kp][kq][jr][kn][qq][qp][po][qk]
AB[ce][ci][cq][dq][ep][gp][go][ho][ko][lo][lp][lq][kr][ls][mr][or][pq][qr][oc][qd]
TR[ci]
C[Problem 80. White to play.  

Black has just played the marked stone. This is a big point, but Black's six stones at the bottom left are still insecure. What should White do ? ]
(;W[fq]
TE[2]
C[Correct Answer.  

White 1 is an important point because it takes away Black's eye shape. Next ... ]
;B[do]
C[Black will first play a forcing move with 2 to avoid being cut into two, ... ]
;W[cm];B[hm]
C[... then jump into the center with 4. Black's stones are vulnerable, but there is not a good way to attack them yet. ]
;W[qh]
LB[fq:1]
C[Therefore, White should take her time and simply play a big point on the right side with 5. White 1 in the Correct Answer not only robs Black of his base, it also ensures that White's group has two eyes. For example, ... ]
;B[ir]
C[... if Black attacks with the sequence Black 6, ... ]
;W[iq]
C[... White 7, ... ]
;B[js]
C[... Black 8, ... ]
;W[jq]
C[... White plays at 9 and she is alive. <= ]
)
(;W[qh]
C[Failure.  

Locally, White 1 is a good move, but ... ]
;B[fq]
LB[iq:A]
C[... Black can secure his stones with 2. Black's prospects are now quite good. If the white stones later need two eyes, White will have to come back to play A, so this bad aji will be a burden. <= ]
)
)
(;
GM[1]
SZ[19]
AW[bc][cd][ce][de][ff][ef][dj][cn][dp][pn][qn][qk][oc][od][oe][pd][qe][ld][ic]
AB[cb][cc][dd][ec][ee][fe][ge][fq][iq][np][pp][qo][qi][qb][qc][rc][qd][pc][nd][pe][pf]
C[Problem 81. Black to play.  

How should Black attack the three white stones in the lower right ? ]
;B[ok]
TE[2]
C[Correct Answer.  

The cap of Black 1 is severe. ]
(;W[pj]
C[If White tries to get out into the open with 2, ... ]
;B[of]
C[... Black forces with 3, ... ]
;W[ne];B[ni]
C[... then blocks White's access to the center with 5. White's stones are still insecure. <= ]
)
(;W[nl]
LB[ok:1]
C[Variation.  

In response to the cap of Black 1, White tries to make shape with 2 ... ]
;B[pl];W[nn]
C[... and 4. But, ... ]
;B[ql];W[rn];B[ro];W[rl];B[rm];W[qm];B[rk];W[sm];B[pk]
C[... with the sequence to 13, Black secures the lower right corner and a large territory on the right side. ]
;W[jp]
C[White tries to get some play with 14 ... ]
;B[jq];W[kp]
C[... and 16, but her stones ... ]
;B[om];W[on];B[ho];W[ln]
LB[nc:C][kc:B][kl:A]
C[... are still insecure with only one eye even after she jumps to 20. Black has several options. He can immediately attack at A, but he might first want to invade at B or C, then, depending on how the game continues, attack at A. <= ]
)
(;W[nm]
C[Variation.  

The knight's move of White 2 is another possible response. ]
;B[mo]
C[After exchanging 3 ... ]
;W[ml]
C[... for 4, ]
;B[oi]
C[... Black makes shape with 5. ]
;W[ol]
LB[on:C][ql:B][pl:A]
C[White must defend against the sequence Black A - White B - Black C with 6, so ... ]
;B[nk]
C[... Black can further strengthen his stones with 7. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cb][db][ec][ed][dd][cd][cg][hp][ip][gq][gs][hr][fr][er][dr][dq][eq][cq][qp][rq][sp][ro][po][qn][qj][nc][nd][ob][pb][pc][qc][rb][sb]
AB[cc][dc][eb][fa][fc][gb][ic][cj][ds][cr][bq][cp][dp][ep][fp][fq][gp][ho][nq][pq][pp][qq][qh][rc][sd][re][qd][pd][od][oc][mc][mb][nb]
TR[nd][nc]
C[Problem 82. Black to play.  

What should Black do about the two marked stones ? Should he capture them in a ladder or is there something else he can do ? ]
(;B[pj]
TE[2]
C[Correct Answer.  

Black 1 and ... ]
;W[qk];B[qi]
LB[ne:A]
C[... 3 are moves which take the whole board into account. Capturing the two stones in a ladder with A is small in scale. Next ... ]
;W[oi]
C[White counterattacks with the peep of 4, then ... ]
;B[pi];W[md];B[ld];W[le];B[kd];W[mf]
LB[le:8]
C[... extracts her stones at the top with 8 to 10. Next ... ]
;B[lg]
C[Black attacks the four white stones with 11 and ... ]
;W[ke];B[jg]
C[... 13, then, ... ]
;W[ie]
C[... after White jumps to 14, ... ]
;B[bc]
C[... plays the sequence from 15 ... ]
;W[bb];B[bd];W[be];B[ce]
C[... to 19 to create aji in the upper right corner. Next ... ]
;W[ac];B[hg]
C[Black continues the attack ... ]
;W[ge];B[fd];W[fe];B[fg];W[ef];B[dh]
C[... with the sequence to 27, mapping out a large moyo on the left side. <= ]
)
(;B[ne]
C[Failure.  

Black captures the two white stones in a ladder, but ... ]
;W[cl]
C[... White counters with an invasion at 2. This move also blocks the ladder, so the fighting can become quite complicated. <= ]
)
(;B[ej]
LB[cl:A]
C[Failure.  

Black 1 prevents the invasion at A and, if you lack confidence in fighting, this is also a good move. But, compared to the Correct Answer, it is a bit slack. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][ec][cd][cf][cg][qc][oc][re][qp][pq][np][rn][qn][pn][on][om][mn][mm][ml][nl][lk][lj][kl][pl]
AB[dg][df][dh][ed][fc][gd][mc][ne][pe][ep][jp][po][qo][nm][ll][lm][km][mk][nk][ok][ol][pk][qk][pm][qm][rm]
C[Problem 83. White to play.  

That is the position reached in the game of Problem 73. How should White attack the three black stones ? ]
(;W[jm]
TE[2]
C[Correct Answer.  

White should play a two-step hane with 1. ]
;B[jl];W[kk];B[jn];W[im];B[ko]
C[After the sequence to Black 7, ... ]
;W[ik]
C[... White secures her stones in the center with 7. These stones aim at the bottom and the top. White is now ahead, so she doesn't have to do anything drastic. <= ]
)
(;W[jj]
C[Failure.  

White 1 is a slack move. ]
;B[jl]
C[Black gets a good position at the bottom with 2. ]
;W[kh]
C[White jumps to 3, ... ]
;B[kf]
C[... but Black answers with 4, mapping out territory at the top. White is under attack. ]
;W[nh]
C[She expands to the right, but ... ]
;B[ph]
C[... Black defends and takes more territory there. White's stones are still vulnerable, so Black can look forward to an interesting game. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ec][eb][ed][dd][cd][ce][be][ci][dp][dn][jc][mc][qg][oh][oj][qj][ro][qp][qq][qr][pr][np][op][oo][po][nn][gp][hq][jq][jr][kr][kp][lp][lq][mr]
AB[bc][cc][dc][bd][fc][cf][oc][pd][qe][qh][ph][pg][ql][qn][rn][qo][or][oq][pq][pp][nq][mq][mp][mo][lo][no][mn][jo][jp][ho][fq][ir][hr][iq]
TR[oh][oj][qj]
C[Problem 84. Black to play.  

How should Black attack the three marked stones ? ]
(;B[mh]
TE[2]
C[Correct Answer.  

Capping with Black 1 is severe. ]
;W[mj]
C[If White 2, ... ]
;B[ki]
C[... Black continues the attack with the knight's move of 3. ]
;W[nh]
C[White tries to get some play with 4 ... ]
;B[mi];W[nf]
C[... and 6, but ... ]
;B[kd]
C[... Black leans on the White stones at the top with 7 ... ]
;W[pf];B[qf];W[kc];B[md]
C[... and 11. White is in trouble. <= ]
)
(;B[oi]
C[Failure.  

If Black wedges in with 1, ]
;W[nj];B[ni];W[mj];B[mi];W[lj]
LB[mi:5][ni:3]
TR[mc][jc]
C[... White easily escapes with the sequence to 6. The wall Black gets with 3 and 5 is ineffective because it is neutralised by the two marked stones at the top. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cd][dg][hd][ie][jf][kf][mg][mf][lg][od][co]
AB[cb][ec][fd][lf][le][ke][je][me][ld][jc][mc][qd][pp]
C[Problem 85. Black to play.  

How should Black play in this position ? ]
;B[if]
TE[2]
C[Correct Answer.  

Black should cut at 1. ]
;W[hf]
C[White ataris with 2 to rescue her stones at the top. ]
;B[ig];W[kg]
C[After White connects with 4, ... ]
;B[eg]
C[... Black leans on the left-side stones by attaching with 5. ]
(;W[hg]
C[White must push out with 6, ... ]
;B[dh]
C[... and Black takes the initiative on the left with 7 ... ]
;W[ch];B[ci]
C[... and 9. ]
;W[cg];B[di];W[ee]
C[White expands her eye space with 12 ... ]
;B[fe];W[ef]
C[... and 14, ... ]
;B[ff];W[ih]
C[... then secures the center with 16. See Problem 129 for Black's continuation. <= ]
)
(;W[dh]
TR[eg]
C[If White defends against the attachment of the marked stone by extending to 6, ... ]
;B[df]
C[... Black will exchange 7 ... ]
;W[cf]
C[... for 8, ... ]
;B[hg];W[gf];B[gg];W[ff];B[ef];W[fg];B[fh];W[eh];B[fe]
C[... then trap the white stones at the top with the sequence to 17. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cb][db][dc][ea][fb][gc][jc][qf][qh][qi][pj][pl][qn][rp][jp][kp][jm][cq][dp][dn][dl][cj][cg]
AB[lc][pd][qd][pf][ph][qq][pp][np][jq][iq][ho][fq][dr][ej][eg][cc][cd][dd][eb][ec][fd][de][ee]
TR[cb][db][dc][ea][fb][gc][jc]
C[Problem 86. Black to play.  

How should Black attack the marked white stones ? ]
;B[ib]
TE[2]
C[Correct Answer.  

The placement of Black 1 is on the vital point. ]
(;W[ic]
C[Blocking from above with White 2 is best. ]
;B[jb];W[hb]
C[After White 4, ... ]
;B[kc]
LB[jd:A][bb:B]
C[... Black is threatening to peep at A and hane at B, so White's stones are still insecure. <= ]
)
(;W[jb]
LB[ib:1]
C[Variation.  

In answer to Black 1, blocking at 2 seems to be a viable option, but ... ]
;B[ic];W[id];B[jd];W[hc];B[ie];W[hd];B[kd]
C[... Black builds up a large moyo in the center with the sequence to 9. Black ends in sente ... ]
(;W[bc]
C[... since White must make eyes in the corner with 10. <= ]
)
(;W[at]
C[... Black builds up a large moyo in the center with the sequence to 9. Black ends in sente ... ]
;B[hb]
LB[bc:@]
C[What happens if White neglects to play at @ ?  

Black will turn at 11. ]
;W[gb];B[kb]
C[After exchanging 13 ... ]
;W[ha]
C[... for 14, ... ]
;B[fa]
C[... Black throws in a stone at 15. Making two eyes in now problematic for White. ]
;W[ga]
C[If White captures at 16, ... ]
;B[bb]
C[... Black blocks with 17. ]
;W[he];B[if];W[hf];B[hg];W[gg]
C[White tries to get out into the center with the sequence to 22, but ... ]
;B[hh]
C[... White is trapped after Black 23. <= ]
))
)
(;
GM[1]
SZ[19]
AW[fc][cm][dm][em][fm][fn][bn][bo][cp][cq][dq][dr][po][pp][pq][oq][or][lq][oc][pe][id][jc]
AB[dd][cf][dj][ck][co][cn][dn][dp][ep][eo][en][fq][bp][bq][br][cr][qr][pr][qq][qp][qn][nq][kd][kc]
LB[kc:A][jc:B][kd:C]
C[Problem 87. White to play.  

After Black invades at A, White attaches with B, How should White play after Black stands with C ?  

[You will find a supplement to this Problem Diagram as "Problem 142"] ]
;W[jf]
TE[2]
C[Correct Answer.  

Black's two stones at the top are heavy, so White 1 is the perfect attacking point. ]
;B[kf]
C[If Black attaches with 2, ... ]
;W[kg]
C[... White drives Black's stones toward her position in the upper right with 3 ... ]
;B[lf];W[lg]
C[... and 5. ]
;B[mf];W[nh];B[of];W[pf];B[og];W[oi];B[pg];W[qi];B[qg];W[re];B[oe];W[od]
C[White defends with 17, and Black's stones are in trouble. Next ... ]
;B[jg]
C[... Black cuts with 18, ... ]
;W[if];B[jh]
C[... then extends to 20 to get some aji on the outside ... ]
;W[ki];B[md]
C[... before securing his stones with 22. ]
;W[ji]
C[White switches to the center ... ]
;B[hg];W[ii];B[hh];W[fe]
C[... and attacks black's stones with the sequence to 27. ]
;B[ec];W[fb];B[fg]
C[After Black 30, ... ]
;W[om]
C[... White maps out a moyo in the center with 31. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][gc][dj][cn][dp][po][pn][qn][qj][oj]
AB[cf][fq][jp][op][pq][qp][qo][qh][qd][od][kc]
TR[cf]
C[Problem 88. White to play.  

Black has entered White's sphere of influence with the marked stone. How should White respond ? ]
(;W[cd]
TE[2]
C[Correct Answer.  

White 1 not only secures the corner, it also attacks the black stone. ]
(;B[ch]
C[If Black extends to 2, ... ]
;W[cj]
C[... White makes an iron pillar with 3. Black's stones are still under attack. <= ]
)
(;B[ef]
LB[cd:1]
C[Variation.  

If Black responds to White 1 by jumping to 2, ... ]
;W[dg]
C[... White will peep with 3, ... ]
;B[df];W[ge]
C[... then jump to 5. Black's stones are still under attack and an invasion into White's corner in the upper left is no longer possible. <= ]
))
(;W[ce]
C[Failure.  

Attacking with 1 ... ]
;B[df];W[dh]
C[... and 3 is also possible. ]
(;B[ff]
C[If Black jumps to 4, ... ]
;W[be]
LB[ff:4]
C[... White secures the corner with 5. This result is also good for White. But Black will not play 4. <= ]
)
(;B[ch]
LB[dh:3]
C[Black makes sabaki.  

After White 3, Black can attach with 4 ... ]
;W[ci];B[eh]
C[... and 6, ... ]
;W[ei];B[dg]
C[... then atari with 8. ]
;W[di]
C[If White connects with 9, ... ]
;B[fh]
C[... Black can extend to 10. Black has a more resilient shape than in the Correct Answer, so this result is not as good for White. <= ]
))
)
(;
GM[1]
SZ[19]
AW[ed][gf][kd][nd][nc][pp][po][pq][oq][or][kp][cq][cr][dp][do][dj]
AB[dc][cd][df][if][id][oc][pd][pf][pr][qr][qq][qn][qp][nq][dq][eq]
TR[ed][gf]
C[Problem 89. Black to play.  

How should Black attack the two marked stones ? ]
(;B[hh]
TE[2]
C[Correct Answer.  

Attacking with the knight's move of Black 1 is the correct direction. ]
;W[gh];B[gi];W[fh];B[hi];W[dh]
C[After White 6, ]
;B[ic]
LB[fe:A]
C[... Black makes an iron pillar at 7, aiming at A as well as the three white stones on the right. <= ]
)
(;B[ei]
C[Failure.  

Black 1 is not a good move because it doesn't have a good follow-up. ]
;W[hg]
C[After White escapes into the center, ... ]
;B[ej]
C[... Black exchanges 3 ... ]
;W[dl]
C[... for 4, ... ]
;B[ek]
C[... then extends to 5. ]
;W[ig]
TR[id][if]
C[White extends to 6 and the two marked stones are under siege. ]
;B[dk]
LB[jf:A]
C[If Black tries to press his advantage on the left side, White can take control of the top with A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][ce][de][df][gd][gf][hf][je][fh][ck][ek][gk][pq][qn]
AB[cf][dg][eg][ef][gg][hg][ig][ei][fi][cm][cp][eq][qd][oc]
C[Problem 90. Black to play.  

The white stones on the left are thin. How can Black attack them while strengthening his own stones ? ]
;B[fl]
TE[2]
C[Correct Answer.  

Since the Black stones are not at all that secure themselves, Black should first peep at 1, then, ... ]
;W[fk]
C[... after White connects with 2, ... ]
;B[ik]
C[... cap with 3. White's stones are in danger, so she has to scramble to make life on the left side. ]
;W[dm]
C[White now attaches with 4. ]
;B[dn]
C[After exchanging 5 ... ]
;W[em]
C[... for White 6, ... ]
;B[cl]
C[... Black bumps against the white stone with 7. Next ... ]
;W[gi]
C[... White hanes with 8 and ... ]
;B[hj];W[di];B[ci];W[cj];B[gj];W[en];B[do];W[fp];B[fq];W[hp]
C[... manages to extricate her stones with the sequence to 18. In the process, however, Black has secured the lower left corner and his stones above are no longer in danger. ]
;B[lc]
C[Black now takes the big points of 19 ... ]
;W[jc];B[pi]
C[... and 21, and he has a good game. <= ]
)
)
(;
GM[1]
SZ[19]
AW[de][df][cf][cj][cl][cm][cn][co][bp][qq][im][kn][mo][no][np][oq][op][pp][qn][pm][ql][rm][qh][pi][oi][nj][nk][mi][mh][li][ki][kh][pd][nc][kc]
AB[dc][fc][cd][ce][bm][bn][bo][cp][cq][do][eq][pq][pr][or][nq][mr][mp][lp][jo][rl][qj][mk][mj][lh][kg][lf][mg][ni][nh][oh][nf][of][og][qf][rd][qc]
TR[kc][nc][pd]
C[Problem 91. Black to play.  

How should Black attack the three marked stones ? ]
(;B[kb]
TE[2]
C[Correct Answer.  

Attaching with Black 1 in an interesting move.. Next ... ]
(;W[jb]
C[If White plays on the outside with 2, ... ]
;B[lc];W[lb];B[mb];W[ka];B[mc]
LB[hc:b][ic:A]
TR[pd][nc]
C[... Black will capture the two marked stones with the sequence to 7. Black is now threatening to kill the white stones by attacking at A, so White has to play B in gote to ensure that her stones are alive. <= ]
)
(;W[lb]
C[Variation.  

If White blocks on the inside with 2, ... ]
;B[jb]
C[... Black will draw back to 3. ]
;W[ld]
C[After 4, Black continues to attack the white stones with 5, while building territory in the top left, ... ]
;B[id];W[pc]
C[... so White has to play 6 to secure her isolated stones. Again, Black ends in sente. <= ]
))
(;B[ic]
C[Failure.  

Black 1 is the move many players would make, but ... ]
;W[jc]
C[... White easily makes a living group with 2 ... ]
;B[id];W[pc]
C[... and 4. <= ]
)
(;B[ob]
C[Failure.  

If Black slides to 1, ... ]
;W[hc]
C[... White would extend to 2, and again her stones are alive. <= ]
)
)
(;
GM[1]
SZ[19]
AW[qc][dd][df][dj][dp][hq][ho][jo][qq][qp][rq][sp][ro][pn][qn][rn][rm][sn][nm]
AB[pd][pf][jd][fc][jq][lp][pq][pp][po][qo][on][om][ol][pm][qm][rl][ql]
TR[qc]
C[Problem 92. Black to play.  

White has invaded the corner with the marked stone. How should Black respond ? ]
(;B[pc]
TE[2]
C[Correct Answer.  

Black 1 is the correct direction. ]
;W[rd]
C[When White plays 2, ... ]
;B[rf]
C[... Black can jump down to 3 and White is completely confined to the corner. ]
;W[pb];B[ob];W[qb];B[nc]
C[After Black defends at 7, he has a vast moyo in the upper right sector. <= ]
)
(;B[qd]
C[Failure.  

Black 1 is in the wrong direction. ]
;W[pc];B[oc];W[ob];B[nc];W[nb];B[mc];W[rd];B[re];W[rc]
LB[se:B][qf:A]
C[White gets more territory in the corner than she should and Black's moyo at the top is not as large. Moreover, the marked stone is misplaced: it would be better positioned at A. White now has a good endgame move at B. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][gc][hc][ic][kc][kd][le][lf][lg][md][qn][pp][oq][cp][co][cm][cl][dj][di][kh][jh][jo]
AB[pd][pk][nq][nr][no][dq][dp][do][dm][ek][ce][fe][hd][id][jd][if][ke][kf][kg][lh][li][hp]
LB[jo:A]
TR[jh][kh]
C[Problem 93. Black to play.  

White, seemingly unable to decide how to play with his marked stones, makes a probe with A. How should Black attack ? ]
(;B[jm]
LB[qq:A]
TR[jo]

TE[2]
C[Correct Answer.  

Black should cap the marked stone with 1. This move isolates the two stones above. Although Black may not be able to capture this stone, he will be able to reinforce his position before going after the two stones above. In addition, he is aiming at the invasion of A. ]
;W[jq]
C[If White jumps down to 2, ... ]
;B[kp]
C[... Black will peep at 2. ]
(;W[jp]
C[Connecting at 4 is bad, because the three white stones are dead ... ]
;B[hq]
LB[qq:A]
C[... after Black 5. Black still aims at A. ]
)
(;W[ko]
C[White answered Black's peep with 3. This was a resourceful answer. ]
;B[jp];W[ip];B[io];W[iq];B[kq];W[ho];B[in];W[gp]
C[White was able to make sabaki with the sequence to 12. Next ... ]
(;B[gm]
C[Black 13 is a calm move. ]
;W[fq]
C[White must play at 14 to live, ... ]
;B[fi]
LB[qq:A]
C[... but Black 15 surrounds a vast framework of territory. Next, Black can aim to invade the lower right corner at A. Black has a won game. <= ]
)
(;B[fq]
C[Failure.  

After White 12, it is not a good idea to deprive White of a base with Black 13. ]
;W[gq];B[go];W[hn];B[hm];W[gn];B[fo];W[kr];B[lr];W[fn];B[fp];W[fl]
LB[qq:B][mp:A]
C[The sequence continues to 23, and White has escaped. Next, the peep of White A will be troublesome for Black, and takes away the value of an invasion at B. <= ]
)))
(;B[jq]
TR[jo]
C[Failure.  

Answering the marked stone with Black 1 is submissive. ]
;W[ho]
C[White will force with 2, ... ]
;B[gp];W[jk]
C[... then jump to 4. White should now have no trouble making two eyes within Black's sphere of influence. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ce][ed][fd][gd][hd][id][qc][pc][oc][nc][nq][jp][dp][eq][cm]
AB[cc][ec][fc][gc][hc][od][nd][pd][qd][pi][pp][pq][pn][ch][ck]
C[Problem 94. White to play.  

The white stones in the upper left are thick, but their influence seems to be neutralised by Black's two stones on the left side. What should White do ?  

[You will find a supplement to this Problem Diagram as "Problem 143"] ]
;W[eh]
TE[2]
C[Correct Answer.  

White caps with 1, ... ]
;B[ek];W[dj]
C[... then exchanges 3 ... ]
;B[cj]
C[... for 4. ]
;W[em]
LB[eh:1]
C[White jumps to 5, securing the territory in the lower left. The value of White 1 is that is gives her stones above breathing room. After White 5, ... ]
;B[di]
C[... Black should defend at 6. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cd][dd][gc][qj][oj][pn][qn][po][dp][cn][dj]
AB[kc][od][qd][qh][qo][qp][pq][op][jp][fq][bj][cf]
TR[bj]
C[Problem 95. White to play.  

Black has just played the marked stone. How should White respond ? ]
(;W[ci]
TE[2]
C[Correct Answer.  

White should play 1 ... ]
;B[bi];W[bh]
C[... and 3. ]
;B[ch];W[cg];B[dh];W[bf];B[dg];W[bg]
LB[bh:3][ci:1]
C[With the sequence to 9, Black's stones are split into two groups. This problem is similar to Problem 9. This kind of a position often occurs, so White 1 and 3 is a nice combination to remember. <= ]
)
(;W[cj]
C[Failure.  

The combination of White 1 ... ]
;B[bi];W[bk]
C[... and 3 is often seen, but in this case, ... ]
(;B[ch]
LB[bi:2]
C[... Black is able to stabilise his stones with 2 and 4. <= ]
)
(;B[dh]
LB[ch:@]
C[Failure for Black.  

Instead of playing at @, Black must not jump to 4 here. ]
;W[ci]
C[White can push with 5, ... ]
;B[ch];W[bg]
C[... then make a placement at 7. ]
;B[bh];W[bf]
C[After White 9, Black's stones are without eyes. <= ]
))
)
(;
GM[1]
SZ[19]
AW[dd][df][dj][dp][hq][ho][jo][nm][pn][qn][rn][rm][ro][sn][qp][qq][rq][sp][pc][qc]
AB[jq][lp][pq][pp][po][qo][on][om][ol][pm][qm][ql][rl][oc][pd][fc][jd][pf]
TR[qc]
C[Problem 96. Black to play.  

White extends with the marked stone, how should Black respond ? ]
(;B[ob]
TE[2]
C[Correct Answer.  

When Black descends to 1, ... ]
;W[re];B[rf];W[qe];B[qf];W[pe];B[oe];W[qd];B[od];W[pb]
C[... the sequence to 10 is inevitable. White is alive in the corner, but ... ]
;B[fe]
C[... Black ends up with a vast moyo when he jumps to 11. <= ]
)
(;B[qd]
C[Failure.  

Black can get the corner territory by blocking with 1 ... ]
;W[ob]
(;B[nb]
C[... and 3, but, ... ]
;W[nc];B[od];W[mb];B[pb];W[na];B[qb];W[ld]
C[... after 10, White's stones are secure and the black stones at the top left are vulnerable. <= ]
)
(;B[nc]
LB[ob:2]
C[Failure.  

If Black extends to 3 in response to White 2, the result is the same as in the Failure Diagram in Problem 92. <= ]
))
)
(;
GM[1]
SZ[19]
AW[dd][gc][dj][cn][dp][po][pn][qn][qj][oj]
AB[cc][fq][jp][op][pq][qp][qo][qh][qd][od][kc]
TR[cc]
C[Problem 97. White to play.  

Black invades the corner with the marked stone. How should White respond ? ]
;W[cd]
TE[2]
C[Correct Answer.  

White should block at 1 and build a moyo in the upper left. ]
;B[dc];W[ec];B[eb];W[fb];B[ed]
C[After Black exchanges 6 ... ]
;W[fc]
C[... for 7, ... ]
;B[bd];W[be];B[bc];W[cf]
(;B[db]
C[... Black lives in the corner with the sequence to 12, but ... ]
;W[ee]
LB[mc:A]
C[... White gets a thick position after playing 13. Since she is thick on the left side, White can now aim to invade at A. <= ]
)
(;B[ee]
LB[db:@]
C[Variation.  

Instead of @ in the preceding diagram, Black might first extend to 12 ... ]
;W[df];B[db]
C[... before connection at 14. ]
;W[ff]
C[Next, White traps the two black stones with 15. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][df][dj][dp][hq][ho][jo][qp][qq][rq][sp][ro][rn][pn][qn][sn][nm][rm][pc][ob]
AB[jq][pq][pp][po][qo][on][om][ol][pm][qm][ql][rl][pd][oc][fc][jd][pf][lp]
LB[ob:A]
C[Problem 98. Black to play.  

What should Black do when White hanes at A ? ]
(;B[od]
TE[2]
C[Correct Answer.  

Connecting at Black 1 is the joseki move. ]
(;W[qc];B[nb];W[re];B[rf];W[qe];B[qf];W[pb]
C[White lives in the corner with the sequence to 8, but ... ]
;B[mc]
C[... Black gets a massive moyo when he connects at 9. <= ]
)
(;W[pb]
C[Variation.  

Connecting at 2 is also a joseki move. ]
;B[nb];W[qd];B[qe];W[rd];B[mc]
LB[rb:A]
C[After 7, Black's moyo is almost as large as in the Correct Answer. White has an opening into Black's moyo in the upper right, but this is compensated for by the bad aji White has if Black plays at A. (See Get Strong at Life and Death, Problem 101.) <= ]
))
(;B[pb]
C[Failure.  

The atari of Black 1 is also a joseki move, but, ... ]
;W[qc];B[qb];W[od];B[nc];W[nb];B[rb];W[qd];B[pe];W[mc];B[nd];W[me];B[ne];W[nf];B[md];W[ld];B[oe]
(;W[le]
LB[lb:A]
C[... after the sequence to White 18, Black's moyo has been drastically reduced. Instead of 18, White could also play A. ]
;B[lc]
C[The atari of Black 9 is small. ]
;W[kc]
(;B[mb];W[lb];B[mc];W[kd]
C[Moreover, Black's stones at the top left are weakened after White connects at 6. <= ]
)
(;B[lb]
C[Black might be able to get more profit by descending to 21, ... ]
;W[kd];B[mb]
C[... then capture with 23, ... ]
;W[je]
C[... but the two black stones at the top left are even weaker than in the preceding diagram after White 24. <=: ]
))
(;W[lb]
LB[le:@]
C[If White chooses to defend at 18, instead of @, ... ]
;B[le]
C[... Black can increase the size of his moyo by cutting at 19. ]
;W[ke]
C[White will then atari at 20 ... ]
;B[lf];W[kd]
LB[jc:A]
C[... and connect at 22, aiming next to play A. Black gets a moyo, but at the expense of weakening his two stones at the top. <= ]
))
)
(;
GM[1]
SZ[19]
AW[cb][dc][eb][fd][kc][oc][di][cj][cn][co][dp][cq][cr][rp][rq][qq][pq][nq][qn]
AB[qd][pe][cc][cd][de][ch][cl][el][bn][dr][fq][iq][op][pp][qp][qo][ro][pl][pi]
TR[di][cj]
C[Problem 99. Black to play.  

How should Black attack the two marked white stones ? ]
(;B[fj]
TE[2]
C[Correct Answer.  

Black should drive White towards the top with the knight's move of 1. ]
;W[dh]
C[After exchanging 2 ... ]
;B[cg]
C[... for 3, ... ]
;W[fh]
C[... White jumps to 4. ]
;B[hi]
C[Black keeps up the attack with 5, and, ... ]
;W[ff]
C[... after White 6, ... ]
;B[fn]
LB[jh:B][hg:A]
C[... jumps to 7 to make a moyo in the lower left. If White A, Black will jump to B. <= ]
)
(;B[ff]
C[Failure.  

Black 1 certainly keeps the white stones from linking up to their allies at the top, but ... ]
;W[dh];B[cg];W[gi];B[hk];W[ii];B[jk];W[ki]
LB[fh:C][gg:B][ef:A]
C[... White easily escapes into the center with the sequence to 8. Black's prospects for making a moyo at the bottom are no longer realistic because Black must defend against White A. If Black B, White C keeps the threat A viable. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ec][ed][qq][pq][op][kq][cp][dp][dn][ep][fp][eq][gq][hq][bh][ci][cg][dg][ef][ff][di]
AB[dc][cd][ic][pd][pm][qp][ro][rq][fq][gp][fo][fr][er][dr][cq][df][cf][bf][bg][eg][eh][gh]
LB[eg:A][ff:B][eh:C][di:D][gh:E]
C[Problem 100. White to play.  

Black plays the sequence to E, isolating the white stones at the top. But Black's stones in the center are also weak. What should White do ?  

[You will find a supplement to this Problem Diagram as "Problem 144"] ]
;W[ie]
TE[2]
C[Correct Answer.  

White should attack the black stone at the top by capping with 1. ]
(;B[kd]
C[If Black responds with 2, ]
;W[ih]
C[... White goes on the offensive against the three black stones in the center with 3 ... ]
;B[fj];W[ik]
C[... and 5. Black is in trouble. ]
(;B[dk]
TR[ik]
C[After White plays the marked stone, Black might try to attack the white stones in the upper left by invading with 6. ]
;W[ck];B[cl];W[dl];B[cj];W[bk];B[el];W[dm];B[dj];W[bj]
C[However, White easily links up with the sequence to 15. ]
;B[fl];W[ej];B[ek];W[ei];B[fi];W[gk]
C[After peeping at 21, ... ]
;B[fk];W[hg]
C[... White makes a reinforcing move with 23 and the black stones are trapped within White's sphere of influence. <= ]
)
(;B[hg]
C[Variation.  

Since White is thin in the center, Black can escape with 6 ... ]
;W[ke];B[ig]
LB[ke:5]
C[... and 8, but Blacks stones become at the top become  vulnerable after White 5. Next ... ]
;W[jd]
C[... White plays 9. ]
;B[he]
C[If Black tries to capture the white stones in the top left by attaching with 10, ]
;W[hd];B[id];W[hf];B[ge];W[gf];B[if];W[je];B[gd];W[jc];B[gc];W[ib];B[hc];W[fb];B[gb];W[ga];B[ha];W[fa];B[hb];W[jb]
C[... he will find himself caught up in a capturing race that he has no hope of winning. This would be a disaster for Black. <= ]
))
(;B[ih]
LB[ie:1]
C[Variation.  

If Black answers the cap of White 1 by jumping to 2, ... ]
;W[jc]
C[... White will attack the top ... ]
;B[jb];W[jd];B[kb];W[lc];B[lb];W[mc];B[mb];W[hc];B[hb];W[id];B[ib];W[nc]
C[... with the sequence to 15. ]
;B[ob]
C[After Black defends the corner with 16, ... ]
;W[hi];B[hh];W[fj];B[kh];W[jj]
C[... White maps out a moyo in the lower left with the sequence to 21. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][ce][dp][dn][pn][qn][ql][qc][pc][nc][nb][rj]
AB[fq][jp][np][pp][qo][pj][ok][lc][me][od][pd][qd]
LB[ok:A][rj:B]
C[Problem 101. Black to play.  

The diagonal move of Black A looks slack, since it seems as if White can slide into Black's moyo at the top with B. How should Black continue ? ]
;B[ri]
TE[2]
C[Correct Answer.  

Black should attach with 1, ... ]
(;W[qi];B[rk]
C[... then clamp with 3. ]
;W[rh]
LB[ri:1]
C[White traps the stone at 1, but ... ]
;B[qk]
LB[qj:A]
C[... after Black 5 the white stones below and above are under attack. Note that Black has avoided to play an atari at A because if White captures this stone she will have an easier time making a second eye. <= ]
)
(;W[qj]
LB[ri:1]
C[Variation.  

In answer to Black 1, White might try to secure her stones ... ]
;B[qi];W[nl];B[ol];W[om]
C[... with the sequence to 6. ]
;B[ro]
C[But Black secures the corner with 7, while denying White room to make two eyes. ]
;W[pi]
C[White tries to get some play above with 8 ... ]
;B[oi];W[ph];B[qg];W[pg];B[qf];W[mj]
C[...to 14, but ... ]
;B[oh];W[mm]
C[... she must eventually come back and defend with 16 to ensure that her stones in the lower right are connected. ]
;B[lp]
C[Black ends the sequence with 17, having secured the territory at the bottom and in the upper right. For all of White's intense maneuvers, she has only managed to escape with her stones. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cc][bc][gc][qj][oj][qn][pn][po][dp][cn][dj]
AB[cd][ce][de][kc][od][qd][qh][qo][qp][pq][op][jp][fq]
LB[cd:A][cc:B][ce:C][bc:D][de:E]
C[Problem 102. White to play.  

How should White play after the skirmish to Black E in the upper left ? ]
(;W[ed]
TE[2]
C[Correct Answer.  

White should calmly extend to 1, ... ]
;B[ch]
C[... allowing Black to extend to 2. ]
;W[cj]
C[White then secures the lower left with 3. ]
;B[eh]
C[In the end, Black must secure his stones by jumping to 4. <= ]
)
(;W[cg]
C[Failure.  

The pincer of White 1 is not good. ]
;B[ed]
C[Black can get good shape by playing an atari at 2, ... ]
;W[dc];B[ff]
LB[ee:B][dg:A]
C[... then jumping lightly to 4. Black could also make sabaki by attaching at A or connecting at B. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][qf][qi][rn][qp][qq][or][dr][er][eq][fr][bm][cm][dn][co][dp][bp][cp][em]
AB[qd][oc][pl][pp][po][mp][bq][cq][dq][fq][gq][ep][eo][en][dm][dl][dk][cl][bl]
TR[qf]
C[Problem 103. Black to play.  

White has just made the checking extension with the marked stone. What should Black do ? ]
(;B[pj]
TE[2]
C[Correct Answer.  

Black should make a shoulder hit with 1 and build a moyo in the center. ]
(;W[pi]
C[If White pushes up with 2, ... ]
;B[oi]
C[... Black plays a two-step hane with 3 ... ]
;W[oh];B[nh]
C[... and 5. ]
;W[oj]
C[If White ataris with 6, ... ]
;B[ni]
C[... Black connects with 7 and ... ]
;W[pk];B[ok];W[qj];B[nj]
C[... the sequence continues up to 11. Black has mapped out a huge moyo in the center. <= ]
)
(;W[oh]
C[If White plays the knight's move of 2, ... ]
;B[ni];W[nh];B[mi];W[mh];B[li]
C[... Black maps out a moyo with the sequence to 7. ]
;W[eh]
C[In the game from which this problem was taken, White plays 8 to cut down on the scale of this moyo. <= ]
))
(;B[oi]
C[Failure.  

Capping with Black 1 is thin. ]
;W[of]
LB[oj:A]
C[After 2, White can aim at the attachment of A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cc][df][nc][dp][pb][qb][qc][qd][qf][pf][og][ph]
AB[db][fc][fe][lc][pd][ob][oc][pc][pe][pp][qh][of][nf]
LB[qh:A][pf:B][of:C][og:D][nf:E][ph:F]
C[Problem 104. Black to play.  

The position in the top left arose from a popular joseki. Black attacked with A and the sequence continues to White F. How should Black continue to press White ? ]
;B[pi]
TE[2]
C[Correct Answer.  

The hane of Black 1 is the correct continuation. Next, ... ]
(;W[oi]
C[White 2 ... ]
;B[pj];W[oj]
C[... and 4 are not good. ]
;B[pk]
LB[pj:3]
C[Black makes territory along the fourth line with 3 and 5, while White gains nothing for her efforts. <= ]
)
(;W[qi]
C[White might cut with 1, ... ]
;B[qj]
C[... but Black plays 3 ... ]
;W[ri];B[pj]
C[... and 5 in sente. ]
(;W[rh];B[oh]
C[He then confines White's stones to the upper right with 7 ... ]
;W[qg];B[ng]
C[... and 9. This result is also good for Black. <= ]
)
(;W[ng]
C[If White pushes up with 2, ... ]
;B[mg]
C[... Black must hane at 3. ]
;W[mf]
C[White cuts with 4, ... ]
;B[nd];W[oi];B[pj];W[oj];B[pk];W[ok]
LB[oj:8][oi:6]
C[... reinforces her stones with 6 to 10, ... ]
;B[pl];W[me]
C[... then switches to the top ... ]
;B[md];W[kf]
LB[lg:A]
C[... with the sequence to 14. With all of his stones secure, Black can now fight by extending to A. <= ]
)
(;W[rj]
LB[rh:@]
C[Variation.  

Instead of 6 at @, Black should not turn at 6 here. If he does, ... ]
;B[oh];W[pg];B[ng]
C[... Black 9 will become sente, ... ]
;W[rg];B[fg]
LB[ql:A]
C[... so Black can expand his moyo with 11, while attacking White's position an the left side. If Black later comes back to defend the lower right, the shape move is A. <= ]
))
)
(;
GM[1]
SZ[19]
AW[dd][dj][dn][dp][jc][nc][ph][og][op][oq][pq][or][qp][rp][qq]
AB[pd][pf][pj][nh][fq][jp][pp][oo][po][qo][ro][np][nq][nr][mn]
LB[nh:A][og:B]
C[Problem 105. Black to play.  

Black A is not seen very often, but it is a valid move. How should Black continue after White B ? ]
;B[nd]
TE[2]
C[Correct Answer.  

Black 1 directly attacks the stone at the top and, from a distance, the two stones below. ]
;W[md];B[ne];W[oc];B[pc]
C[After the sequence to Black 5, ... ]
;W[ng]
C[... White pushes into the center with 6. ]
;B[mc]
C[Black now plays 7 ... ]
(;W[lc];B[mb]
C[... and 9. ]
;W[lb]
C[After White 10, ... ]
;B[ld]
C[... Black cuts with 11, ... ]
;W[me];B[mf]
C[... then ataris with 13. ]
;W[le];B[mg]
C[After Black 15, the three white stones on the right side are trapped. This leaning attack is similar to the one in Problem 48. <= ]
)
(;W[lg]
LB[lc:@]
C[Variation.  

Instead of @ in the Correct Answer, if White jumps to 8 here, ... ]
;B[ld];W[me];B[mf];W[le];B[mg]
C[... Black could play the sequence to 13 and trap the white stones on the right side. <= ]
)
(;W[mg]
C[Variation.  

If White 8 here, ... ]
;B[lc]
C[... Black secures the top with 9. <= ]
)
)
(;
GM[1]
SZ[19]
AW[de][cf][dg][ck][jq][pq][np][nn][pl][pc][qd][kc]
AB[dc][fc][cd][ce][cp][eq][om][pn][qo][rq][qi][qf]
C[Problem 106. Black to play.  

White has just extended with the marked stone. What should Black do ?  

[You will find a supplement to this Problem Diagram as "Problem 145"] ]
;B[oj]
TE[2]
C[Correct Answer.  

The knight's move of Black 1 secures a large territory on the right side for Black. The white stone there can't escape. ]
;W[cn]
C[Even if White plays at A next, Black still has the initiative. <= ]
)
)
(;
GM[1]
SZ[19]
AW[bc][cc][dd][ed][gc][qj][oj][qn][pn][po][dp][cn][cj][dj]
AB[kc][od][qd][qh][qo][qp][pq][op][jp][fq][fo][ch][cd][ce][ef]
LB[eh:A][fo:B]
C[Problem 107. White to play.  

Instead of securing his stones at A, Black jumps to B. How should White attack the black stones on the left ? ]
;W[dg]
TE[2]
C[Correct Answer.  

White 1 is the vital point. ]
;B[cg]
C[If Black defends at 2, ... ]
;W[df]
C[... White plays 3 ... ]
;B[de];W[ee]
C[... and 5. and the black stones are in trouble. White is threatening to play A, but, if Black defends there, his stones will have a hard time making two eyes. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][dd][df][dp][nc][pb][qb][qc][qd][qf][pf][ph][og][ng][mf][lf]
AB[pp][db][fc][fe][lc][nd][ob][oc][pc][pd][pe][of][nf][qh][pi][mg]
LB[lf:A]
TR[mg]
C[Problem 108. Black to play.  

In answer to the marked stone, White extends to A. What should Black do next ? ]
(;B[nh]
TE[2]
C[Correct Answer.  

Black 1 is the key point. ]
(;W[rg]
C[In answer to Black 1, White must defend her corner territory with 2. ]
;B[mh];W[kg];B[ki]
C[Black chases the group at the top with 5, making influence in the center. ]
;W[ig];B[jd]
C[He then defends the top with 7. Black should be quite satisfied with this result. <= ]
)
(;W[mh]
C[Suppose White subdues this stone with 2 ... ]
;B[lg];W[ni]
C[... and 4. ]
;B[qe]
C[Black would then cut through with 5 ... ]
;W[re];B[rf]
C[... and 7, ... ]
;W[rg];B[qg]
LB[pg:A]
C[... then atari at 9. White can't play at A because she is short of liberties, so ... ]
;W[sf]
C[... she has to capture with 10. Next, ... ]
;B[pg]
C[... Black ataris with 11 ... ]
;W[oh];B[oi]
C[... and 13, and ... ]
;W[nh];B[lh];W[nj];B[rf]
C[... and the sequence continues up to Black 17. White ends up with a weak group in the center and two weak stones at the top. Black has a huge advantage. <= ]
))
(;B[mh]
C[Failure.  

Black 1 is ineffective. ]
;W[oi]
C[Even though the sequence from White 2 ... ]
;B[pj];W[oj];B[pk];W[ok];B[pl]
C[... Black 7 gives Black profit on the right side, ... ]
;W[kg]
C[... Blacks two stones in the center are under attack when White plays 8. Comparing this diagram with the Correct Answer, it should be clear that this result is unsatisfactory for Black. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cb][dc][eb][ed][jd][jc][kc][jf][qf][qk][qn][dq][eq][cp][cn][cj]
AB[cc][cd][ce][kd][ld][lf][mc][qd][pd][qp][pq][jp][ch][ep][fp][fq]
TR[jf]
C[Problem 109. Black to play.  

White has jumped into the center with the marked stone. What should Black do ? ]
;B[qi]
TE[2]
C[Correct Answer.  

Black is strong above and below, so he can invade White's thin position with 1. ]
;W[ph];B[pi];W[nh];B[oi];W[oh];B[lh];W[ni]
C[If White plays the sequence to 8, ... ]
;B[pk]
C[... Black leans on the white stone below with 9. Next ... ]
;W[pl]
TR[pk]
C[... White answers the marked stone with 10. ]
;B[ok];W[mj];B[ol];W[pm];B[rk];W[rl];B[qj];W[ql];B[ml];W[kj];B[ro];W[rj];B[ri];W[sk];B[oo];W[rn]
C[When White plays 26, her stones are alive, but Black has built up a moyo at the bottom. ]
;B[jg]
C[After 27, White's stones are still insecure. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ec][dc][cd][de][ob][oc][od][pc][qc][rc][rd][ne][of][qf][dq][do][mq][nq][pq][qq][rq][rp][qn]
AB[fd][ed][fc][jc][nb][nc][nd][qd][pd][pe][oe][re][rf][qg][ph][jq][mo][op][pp][qp][qo][ro][pn]
TR[pc]
C[Problem 110. Black to play.  

White has just secured her corner by connecting with the marked stone. What should Black do next ? ]
;B[me]
TE[2]
C[Correct Answer.  

Black should atari with 1, ... ]
;W[nf]
(;B[nh]
C[... then attack with 3. ]
;W[mf];B[le];W[lf]
LB[mf:4]
C[White runs away with 4 and 6, ... ]
;B[ke]
LB[le:5]
C[... inducing Black to secure his territory at the top with 5 and 7. ]
;W[lh]
C[Next, White jumps to 8 and ... ]
;B[mj]
C[... Black turns his moyo on the right into territory. <= ]
)
(;B[mf]
C[Failure.  

Black could drive the white stones toward the bottom with 3. ]
;W[oh];B[oi];W[nh];B[lh];W[ni];B[oj];W[nj];B[ok]
C[Black secures territory on the right with 11. ]
;W[lj];B[ji]
TR[de]
C[After 13, White's stones are still in danger, but Black's moyo at the top is wide open and, with the marked stone in place, its scope is limited. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dc][df][ch][bg][co][dp][gq][jq][rp][rn][sn][sm][qm][ql][rl][qk][qj][pj][qi][ri][qh][qd][rd][qa][pa][pb][pc][oc][od][oe][mb][mc][lc][kc][kd][kb][jb][hb][hj][nk]
AB[bh][cj][cm][oq][qp][qn][qo][ro][so][rh][sg][rf][re][qe][pe][pd][qc][rc][qb][ra][ne][nf][md][ld][nb][ib][ic][jc][jd][je][ke][fc][fe][gi][pk][ok][oj][ol][pi][ph]
TR[hj]
C[Problem 111. Black to play.  

White has just played the marked stone in an attempt to reduce Black's moyo. What should Black do ? ]
;B[gj]
TE[2]
C[Correct Answer.  

Black should exchange 1 ... ]
;W[hk]
C[... for 2, ... ]
(;B[ip]
C[... then lean on White's stones at the bottom with 3 ... ]
;W[iq];B[gp]
C[... and 5. ]
;W[hp];B[ho];W[hq]
C[After the sequence to 8, ... ]
;B[fl]
C[... Black can play 9, and the two white stones in the center are trapped inside Black's moyo. <= ]
)
(;B[eq]
C[Failure.  

The game continued with Black 3 ... ]
(;W[dq];B[dr]
C[... and 5. These moves were not good because it gave White a chance to rescue her two stones in the middle. ]
;W[cr];B[gp]
C[Black resumes the attack with 7. <= ]
)
(;W[ep]
LB[eq:3]
C[White's best strategy.  

After Black invaded at 3, White should force Black to live in the corner ... ]
;B[fq];W[gp];B[cq]
C[... with the sequence to 7. White ends in sente, so her two stones in the center can now easily escape; Black's moyo has been erased. <= ]
))
)
(;
GM[1]
SZ[19]
AW[dd][ce][be][df][ef][cg][ch][bo][co][dp][fp][nq][kq][pr][qb][qc][pb][pd][pe][jd]
AB[cc][dc][fc][cf][bf][bg][bh][cj][dh][dg][bn][cn][en][qq][pp][pn][qi][pc][oc][qd]
C[Problem 112. Black to play.  

How can Black take the initiative at the top ? ]
;B[gf]
TE[2]
C[Correct Answer.  

The sequence ... ]
;W[ed];B[gb];W[eh];B[fe]
C[... to Black 5 severely attacks the white stones in the upper left. ]
;W[gh]
C[After White escapes to 6 ... ]
;B[md]
C[... Black jumps to 7, forcing ... ]
;W[qf]
LB[qe:A]
C[... White to defend at 8 (Black is threatening to play A). Next, ... ]
;B[ke]
C[... Black attacks the lone white stone at the top with 9. ]
(;W[ih]
C[White now needs to defend her stones in the center with 10. ]
;B[hi]
C[After exchanging 11 ... ]
;W[hh]
C[... for 12, ... ]
;B[if]
C[... Black secures the top with 13. <= ]
)
(;W[if]
C[Variation.  

If White runs away by jumping to 10 here, ... ]
;B[hg]
C[... Black keeps the white stones on the left separated from its allies at the top with 11. ]
;W[kf];B[lf];W[kg];B[je];W[ie];B[kd];W[jc];B[lg];W[kh];B[mi]
LB[jf:A]
C[After Black 21, White's stones on the left and at the top are under attack. The defect in White's shape at A will be a burden. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][dq][cn][nc][pb][qb][qc][qd][qf]
AB[eb][fd][de][be][pp][pd][pe][pc][oc][ob]
TR[be]
C[Problem 113. White to play.  

Black has just secured the corner with the marked stone. What should White do ?  

[You will find a supplement to this Problem Diagram as "Problem 146"] ]
;W[ne]
TE[2]
C[Correct answer.  

White should press her advantage on the right side, attacking the five black stones by jumping to 1. Next ... ]
;B[pf]
C[Black presses against the white stones with 2 ... ]
;W[qg];B[pg]
C[... and 4, but ... ]
;W[ng]
C[... White continues the attack with 5. White is building influence in the center, but Black is gaining nothing. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][kc][dp][do][dq][eq][er][fp][ip][no][oo][po][qp]
AB[pc][qe][dr][cr][cq][cp][cn][fq][kq][mp][oq][on][pn][qn]
TR[mp]
C[Problem 114. White to play.  

Black has reinforced his stones at the bottom with the marked stone. How should White respond ? ]
(;W[pq]
TE[2]
C[Correct Answer.  

This is a case where White must defend to ensure that her weak stones don't come under attack. White 1 is the vital point for White to make a base in the corner. Next, ... ]
;B[pr]
LB[pq:1]
C[Besides securing a base for her stones, White 1 also attacks the black stones. Black must defend with 2 ... ]
;W[qr];B[or]
C[... and 4. ]
;W[ro]
C[White now secures the corner with 5, and ... ]
;B[pj]
C[... Black will extend to 6, staking out a position on the right side. <= ]
)
(;W[pj]
C[Failure.  

White 1 is bad. ]
;B[qr]
C[Black slides to 2, expanding his territory and robbing the four white stones of their base. White must escape, but with weak stones above and below, she is sure to fall behind as she tries to rescue them. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dc][df][ch][bg][co][dp][dq][cr][hp][gq][jq][rp][rn][sn][sm][qm][ql][rl][qk][qj][pj][qi][ri][qh][qd][rd][qa][pa][pb][pc][oc][od][oe][mb][mc][lc][kc][kd][kb][jb][hb][hj][nk][hk]
AB[bh][cj][cm][oq][qp][qn][dr][eq][gp][qo][ro][so][rh][sg][rf][re][qe][pe][pd][qc][rc][qb][ra][ne][nf][md][ld][nb][ib][ic][jc][jd][je][ke][fc][fe][gi][pk][ok][oj][ol][pi][ph][gj]
TR[hp]
C[Problem 115. Black to play.  

White has just played the marked stone. What should Black do ? ]
(;B[go]
TE[2]
C[Correct Answer.  

Black should extend to 1. ]
;W[ho]
C[If White 2, ... ]
;B[hn]
C[... Black hanes with 3. ]
;W[gn]
C[When White cuts with 4, ... ]
;B[gm];W[fn];B[fm]
LB[gm:5]
C[... Black plays 5 and 7. ]
;W[en]
C[White must play 8n to save her two stones, so ... ]
;B[in]
TR[hk][hj]
C[... Black extends to 9, trapping the two marked stones. <= ]
)
(;B[fp]
C[Failure.  

In the game, Black drew back with 1, and ... ]
;W[ho]
C[... White exchanged 2 ... ]
;B[fn]
C[... for 3. ]
(;W[dm]
C[Attaching with White 4, however, was a mistake. ]
;B[hm]
C[Black again goes on the offensive with 5. ]
;W[gk];B[dn];W[cn]
C[The game continued to White 8. <= ]
)
(;W[hm]
TR[fn]
C[White's best move.  

After Black jumped with the marked stone, White should have jumped to 4, linking up with her two stones in the center. White now has a won game. <= ]
))
)
(;
GM[1]
SZ[19]
AW[cd][bd][dd][dc][eb][fb][fc][cl][dn][dp][eq][qj][oe][hg][hf][he][ie][je][ke][ld][jc][ib][nb][nc][ob][nd]
AB[ec][ed][fd][ge][gc][hc][be][cf][dg][fg][dj][el][pp][pb][oc][od][pd][qd][pf][le][me][ne][mg][kf][jf][if]
C[Problem 116. Black to play.  

How should Black play in this position ? ]
;B[ql]
TE[2]
C[Correct Answer.  

Black should drive White in the direction of his thickness above with 1. ]
;W[oj]
C[If White jumps to 2, ... ]
;B[ol]
C[... Black reinforces his position in the lower right with 3. ]
;W[qg]
C[After White extends to 4, ... ]
(;B[pi]
(;W[pj];B[rh]
LB[pi:5]
C[... Black takes profit with 5 ...and 7. ]
(;W[rk]
LB[rh:7]
C[After Black 7, White might play 8, threatening Black's territory below and to cut off the black stone on the second line. ]
;B[rl]
C[Black blocks at 9, and ... ]
;W[qh];B[ri];W[qi]
LB[qh:10]
C[... White cuts through with 10 and 12. ]
;B[rj];W[qk];B[sk]
C[But Black links up with 15. White's stones still don't have eyes. <= ]
)
(;W[qi]
LB[rh:7]
C[White 8 is not a good answer to Black 7. ]
;B[qh];W[ph];B[rg]
LB[qh:9]
TR[pi]
C[Black plays 9 and 11. White is left with the bad aji of the marked stone and her stones still lack eye shape. This result is unsatisfactory for her.  <= ]
))
(;W[oi]
LB[pi:5]
C[When Black plays 5, White might block with 6. ]
;B[ph]
C[Black falls back with 7 and ... ]
;W[pj]
C[... White must connect at 8. ]
;B[ri]
C[Black next jumps to 9 and secures the territory in the upper right. ]
;W[qi];B[qh];W[rj];B[rh];W[lj]
LB[mj:B][rl:A]
C[If White attaches at A, she can make only one eye, so she must run away with 9. White 9 is thin and there is a chance that Black might attach at B, but the ensuing fight could spill over Black's position below. ]
;B[ll];W[jj];B[ki];W[kj];B[jl]
C[Therefore it is better for Black to chase the white stones toward his strong position on the left with 19. Black's result is too good, so White cannot play this way.  <= ]
)
(;W[rl]
LB[pj:@]
C[Instead of @ in the Correct Answer, White could attach with 6 here. Black might be tempted to answer at @, but this is a bit loose. ]
;B[rm]
C[Simply responding with 7 ... ]
;W[qk];B[pl]
C[... and 9 gives Black a strong position in the lower right. <= ]
)
(;W[qi]
C[White can also defend the side with 6. ]
;B[pj]
C[Black would then push trough with 7 ... ]
;W[qk];B[pk]
C[... and 9. ]
;W[rl];B[qm];W[rm];B[qn]
C[White lives on the right, but Black gets a thick wall in the center. This is a satisfactory result for Black.  <= ]
))
(;B[qi]
LB[pi:@]
C[If Black doesn't like the results of the variations after Black @, he can simply attach with 5 and ... ]
(;W[ri];B[pi];W[pj];B[rh];W[rj];B[qh]
C[take the territory in the upper right with the sequence to 11. <= ]
)
(;B[mk]
LB[qi:A][pi:@]
C[Failure.  

Black 5 is not all that bad, but it is not as decisive as the two correct answers @ and A. ]
;W[rl];B[rm];W[rk];B[qm];W[qf]
TR[oe]
C[White lives with the sequence to 10, while Black has secured the territory in the lower right. The aji of the marked stone will be a bit annoying for Black. <= ]
)
(;W[pi]
C[If White presses with 6, ... ]
;B[qh];W[ph];B[rg]
LB[qh:7]
C[... Black will play 7 and 9. Black's stones are secure, but White's are still without a base. <= ]
))
)
(;
GM[1]
SZ[19]
AW[ce][cd][dc][fc][dp][fq][qj][qf][rd]
AB[de][cf][df][dj][cn][pp][ql][pd][nc]
TR[rd]
C[Problem 117. Black to play.  

White has just played the marked stone. What should Black do ? ]
(;B[qh]
TE[2]
C[Correct Answer.  

Black is strong at the top, this is his chance to invade at 1. Black's aim is to attack the lone white stone on the right. ]
;W[of]
C[If White jumps to 2, ]
;B[pi]
TR[qj]
C[... Black plays the diagonal move of 3. The marked stone is now under attack. ]
;W[qc]
C[If White 4, Black simply takes up position at the top with 5. ]
;B[kc];W[pj]
TR[kc]
C[After Black played the marked stone, White will run away with 6 ... ]
;B[ni];W[pl];B[qm];W[oj]
C[... to 10. ]
;B[ng]
C[Black makes shape with 11. ]
;W[mk]
C[White 12 is necessary, so ... ]
;B[nf]
LB[qm:4]
C[... Black can make a wall with 13. Although this result is not decisive for Black, he has managed to strengthen his position with 4 and White's stones still lack eyes. <= ]
)
(;B[qc]
C[Failure.  

Defending the corner with Black 1 is a passive move; Black has failed to disrupt White's position and to take the initiative. ]
;W[ph]
LB[qn:A]
C[White secures her stones with 2. Next, she aims at an invasion at A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ci][ei][fr][fq][eq][gq][dp][cp][eo][bo][cn][lq][lo][rp][qn][qk][pb][ob][nb][nc][oe][pe][qd]
AB[ec][dd][cg][eg][bp][bq][cq][dq][dr][er][ep][nq][pp][qq][rq][qi][mb][mc][md][ic][nd][od][oc][ne]
C[Problem 118. White to play.  

How should White attack the lone black stone on the right side ? ]
(;W[oj]
TE[2]
C[Correct Answer.  

The knight's move of White 1, driving Black into her strong position above, is a good move. ]
;B[oi];W[ni];B[oh];W[nh];B[qg];W[ng]
C[After White 7, ... ]
;B[rj];W[rk];B[rf];W[re];B[rh]
C[... Black makes a living group with the sequence to 12, but ... ]
;W[gh]
C[... White's moyo is enormous after she plays 13. <= ]
)
(;W[oi]
C[Failure.  

White 1 is overly aggressive. ]
;B[pj];W[nk];B[oj];W[nj];B[pl];W[ql];B[ol]
C[Black runs away towards his stones at the bottom with the sequence to 8, but ... ]
;W[on]
C[... White keeps him on the run with 9. Next ... ]
;B[nl];W[lk];B[mm];W[no];B[km]
C[Up to 14, Black breaks into White's moyo. ]
;W[jk]
C[This is extremely risky for White; she now has to kill Black to win. But this is not so easy because Black has a lot to room to maneuver. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cf][qh][ql][pp][jp]
AB[fc][jd][oc][qd][qj][dp]
TR[qh]
C[Problem 119. Black to play.  

White has invaded with the marked stone. How should Black respond ? ]
(;B[pi]
TE[2]
C[Correct Answer.  

Since Black has a strong position at the top. he should attack the white stone with the diagonal move of 1. Next ... ]
;W[qe]
C[White will first play the forcing moves of 2 ... ]
;B[pd];W[rd]
C[... and 4, ... ]
;B[rc];W[og]
LB[se:C][sd:B][rf:A][rd:4][qe:2]
C[... then jump to 6. White 2 and 4 gives White the option of getting eye shape with a ko by playing the sequence White A - Black B - White C. ]
;B[ni];W[mg];B[li];W[kg];B[ji];W[ig];B[hi];W[gg];B[fi]
C[Black boldly chases White up to 15, ]
;W[eg];B[hd]
LB[qn:D]
C[... then defends the top with 17. Black now aims to invade at D. This result is a great success for Black. White has obtained no territory, while Black has built a massive wall in the center. ]
;W[lc]
TR[hd]
C[After Black defends with the marked stone, invading with White 18 is unreasonable. ]
;B[nf];W[ng];B[lf];W[lg];B[jf]
LB[nf:19][lf:21]
C[Black peeps with 19, 21, and 23, ... ]
;W[jg];B[kb]
C[... then plays 25, and the territory at the top belongs to Black. <= ]
)
(;B[oj]
C[Failure.  

Jumping to Black 1 is a slack move. ]
;W[rj]
C[White can easily make sabaki by attaching underneath with 2. <= ]
)
(;B[oi]
C[Failure.  

The knight's move of Black 1 is also slack. ]
;W[pj];B[pi];W[qi];B[pk];W[rj];B[oj];W[qk]
C[White can link up her stones with the sequence to 8. <= ]
)
)
(;
GM[1]
SZ[19]
AW[bb][cb][db][dc][ed][fc][dh][cl][cr][dq][eq][gq][jq][nc][qj][qm]
AB[cc][bc][ad][be][ce][de][dd][df][ec][bq][cq][dp][co][fo][oq][qp][pd][qf]
LB[nc:A][qf:B][qm:C]
C[Problem 120. Black to play.  

White has played the sequence to C on the right side. How should Black continue ?  

[You will find a supplement to this Problem Diagram as "Problem 147"] ]
;B[cj]
TE[2]
C[Correct Answer.  

On the left side, Black is strong above and below, while White's two stones are thin. Therefore, Black should invade at 1. Next ... ]
;W[dj]
C[If White attaches with 2, ... ]
(;B[ci];W[di];B[ch]
LB[ci:3]
C[... Black can link up with his stones at the top with 3 and 5. White's stones are still without eye shape. <= ]
)
(;B[di]
C[Failure.  

Wedging in with Black 3 is not good in this position. ]
;W[ci]
C[White can now secure her stones on the left side by playing 4 ... ]
;B[ei];W[bj]
C[... and 6. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dc][df][ch][bg][co][dp][gq][jq][rp][rn][sn][sm][qm][ql][rl][qk][qj][pj][qi][ri][qh][qd][rd][qa][pa][pb][pc][oc][od][oe][mb][mc][lc][kc][kd][kb][jb][hb][hj][nk][gk][hk][cr][dq][hp][ho][cn][dm]
AB[bh][cj][cm][oq][qp][qn][qo][ro][so][rh][sg][rf][re][qe][pe][pd][qc][rc][qb][ra][ne][nf][md][ld][nb][ib][ic][jc][jd][je][ke][fc][fe][gi][pk][ok][oj][ol][pi][ph][gj][dr][eq][fp][gp][fn][dn][hm]
TR[cn]
C[Problem 121. Black to play.  

In the game in Problem 115, White cut with the marked stone. How should Black continue ? ]
(;B[dl]
TE[2]
C[Correct Answer.  

Black should first atari at 1, ... ]
;W[em];B[fm]
C[... then push with 3 ... ]
;W[el];B[fl];W[ek];B[fk]
C[... to 7. ]
;W[ej]
C[After White 8, ... ]
;B[jm]
C[... Black jumps to 9, staking out a huge territory in the center. Although Black can't get any territory on the left side, he still has some aji there, so White might not be able to claim all the territory there. <= ]
)
(;B[em]
C[Variation.  

Black ataried with 1 ... ]
;W[dl];B[fk];W[cl]
C[... and the game continued with the sequence to 4. Black's stones here are thinner than in the Correct Answer, but White won't get as much territory on the left side. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][cn][dq][pb][qb][qc][qd][qf][qg][nc][ne][ng]
AB[eb][fd][de][be][pp][ob][oc][pc][pd][pe][pf][pg][ph]
LB[ph:A]
C[Problem 122. White to play.  

How should White attack the black stones after Black extends to A ? ]
;W[oi]
TE[2]
C[Correct Answer.  

White should play the shoulder hit of 1. ]
;B[qh];W[qj];B[rh];W[rf];B[qk];W[pk];B[rj];W[ql];B[rk]
C[Black struggles to get a position on the right side, but ... ]
;W[pl]
C[... White gets a lot of influence on the outside with 11. Black, for his part, has gained almost no territory. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dc][df][ch][bg][co][dp][gq][jq][rp][rn][sn][sm][qm][ql][rl][qk][qj][pj][qi][ri][qh][qd][rd][qa][pa][pb][pc][oc][od][oe][mb][mc][lc][kc][kd][kb][jb][hb][hj][nk][gk][hk][cr][dq][hp][ho][cn][dm][cl][dl]
AB[bh][cj][cm][oq][qp][qn][qo][ro][so][rh][sg][rf][re][qe][pe][pd][qc][rc][qb][ra][ne][nf][md][ld][nb][ib][ic][jc][jd][je][ke][fc][fe][gi][pk][ok][oj][ol][pi][ph][gj][dr][eq][fp][gp][fn][dn][hm][em][jm][fk]
LB[jm:A]
C[Problem 123. Black to play.  

This is the position that arose in the game of Problem 121. Black just jumped to A. What should White do ? ]
;W[gm]
LB[jm:A]

TE[2]
C[Correct Answer.  

Black A in the problem diagram is thin. When White attaches with 1 ... ]
;B[gn];W[hn]
C[... and cuts with 3, the black stones in the center are cut off from their allies on the left. ]
;B[hl]
C[Black resists with 4, but ... ]
;W[gl]
C[Black must answer White 5 ... ]
;B[el]
C[... with 6, ... ]
;W[jl];B[in];W[hi];B[gh];W[km]
C[... and Black's position collapses when White blocks with 11. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][dq][cn][pb][qb][qc][qd][qf][qg][nc][ne][ng]
AB[eb][fd][de][be][pp][oh][pg][pf][pc][pd][pe][ob][oc]
LB[oh:A]
C[Problem 124. White to play.  

Black has just played the diagonal move of A. What should White do ? ]
;W[qh]
TE[2]
C[Correct Answer.  

White 1 may be a hard move to see, but it is the key point in this position. ]
;B[nh]
C[Black will push out with 2 ... ]
;W[mh];B[mi]
C[... and 4, ... ]
;W[lh];B[nj]
C[... but he must fall back and make shape with 6. ]
;W[li];B[lj];W[kj];B[lk];W[kk];B[ll];W[kl];B[lm];W[jn]
LB[qh:1]
C[White now bears down on Black with the sequence to 15, building influence in the center. This influence combines well with her enclosure in the lower left corner, while Black's influence facing the right is neutralised by the white stone at 1. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][pb][qb][qc][qd][qf][qg][nc][ne][ng][dq][cn]
AB[eb][fd][de][be][ob][oc][pc][pd][pe][pf][pg][nd][pp]
LB[nd:A]
C[Problem 125. White to play.  

Black wedges in with A. What should White do ? ]
;W[md]
LB[nd:A]

TE[2]
C[Correct Answer.  

Answering Black A with the atari of White 1 is obvious, but ... ]
;B[mc]
C[... White must be careful when Black cuts with 2. ]
(;W[lc]
C[White 3 ... ]
;B[nb];W[mb]
C[... and 5 are the best moves. ]
;B[me];W[ld];B[nf];W[mf];B[oe]
C[The sequence continues to Black 10. ]
;W[lf]
LB[le:A]
C[Here White 12 is the strongest move. White gets an excellent result because Black has gained absolutely no territory, while White has built a thick position on the outside. Later, if White gets to play A, Black might have a hard time to get two eyes. <= ]
)
(;W[nb]
LB[mc:2]
C[Failure.  

Answering the cut of Black 2 by descending to 3 might be good in some situations, but here ... ]
;B[mb];W[na];B[od];W[oa];B[qe];W[re];B[qh];W[rd];B[rh];W[rg];B[sg];W[rf];B[oi]
C[... Black gets a good position on the outside with the sequence to 15. ]
;W[lc]
C[Just like the Correct Answer, White has a strong position in the top right, but here, Black's stones on the right side are secure and work well with his stone in the lower right corner. <= ]
)
)
(;
GM[1]
SZ[19]
AW[eb][dc][cd][df][gd][pb][ob][nc][kc][of][qf][rf][pg][ph][qi][qn][rp][bq][dq][dp][ep][er][cn][cm][dl][dk][fk][hk][jk]
AB[ec][gc][hd][ge][fe][qb][qc][ke][nf][og][pf][pe][pd][qe][pp][nq][eq][gp][fp][eo][do][co][bo][di][fi][dm][em][hm][jm]
TR[rp]
C[Problem 126. Black to play.  

White slides into the corner with the marked stone. What should Black do ? ]
(;B[om]
LB[qm:A]

TE[2]
C[Correct Answer.  

Black jumps all the way out with 1, aiming at A. ]
;W[pl]
C[White defends with 2 and ... ]
;B[ol]
C[... Black pushes with 3, ... ]
;W[pk]
C[... forcing White to extend to 4. ]
;B[gj];W[gk];B[ij];W[ik]
(;B[ki]
C[Black now attacks with the sequence to 9. The white stones on the left are in a pinch. Next ... ]
;W[ci]
C[White has to make eye shape for her stones. She does this by playing at 10 and ... ]
;B[ch];W[bi];B[bh];W[dj];B[dh];W[bk]
LB[fb:A]
C[... playing the sequence to 16. Black ends in sente, and the moyo and territory he has built below and above are enough to win. Next, Black can attack the white stones in the upper left corner by playing A in sente. If Black becomes thick around here, it could affect the white stones in the upper right. <= ]
)
(;B[cj]
C[Failure.  

Attacking White's eye shape with Black 9 is not good. ]
;W[ki]
C[White can take the vital point of 2 and Black won't be able to make much territory at the top. <= ]
))
(;B[pn]
C[Failure.  

Black 1 ... ]
;W[pm];B[on]
C[... and 3 are not good because ... ]
;W[pl];B[gj];W[gk];B[ij];W[ik];B[nl]
C[... Black ends in gote with 9. ]
;W[ki]
LB[ci:A]
C[White can now play 10. In this variation, White still has the option to attach at A. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dq][co][lo][ml][ol][om][pl][on][oo][qo][ro][ne][md][od][qc]
AB[dd][pq][qp][np][no][mn][ln][pm][qm][ql][pk][rc][qd][pe][oe]
C[Problem 127. White to play.  

The white stones in the lower right don't have eyes. What should White do ? ]
(;W[oi]
TE[2]
C[Correct Answer.  

White should attack with 1. ]
;B[qi]
C[Black is forced to submissively defend on the third line with 2. ]
;W[nj]
LB[qh:A]
C[Next, White 3 threatens to attach at A, ... ]
;B[ph]
C[... so Black defends with 4. ]
;W[ng]
C[White can now build influence throughout the center with 5. <= ]
)
(;W[pi]
C[Failure.  

White 1 looks like a tesuji. Players who have studied this move in joseki books would be tempted to play it. But ... ]
(;B[oj]
LB[pi:1]
C[... Black will answer White 1 with the diagonal move of 2. ]
(;W[oi]
C[If White plays the normal moves of 3 ... ]
;B[nj];W[mh]
C[... and 5, ... ]
;B[lj]
C[... her eight stones below are in serious trouble. <= ]
)
(;W[nj]
C[Failure.  

White 1 is crude. ]
;B[pi]
C[It just provokes Black to defend his territory on the fourth line with 2. <= ]
)
(;W[lj]
C[If White 3 here, ... ]
;B[oi]
LB[pi:1]
C[... Black quells the white stone at 1 by playing at 4. <= ]
))
(;B[ok]
C[If Black follows the usual sequence of 2 ... ]
;W[nk];B[oj]
C[... and 4, his stones are in trouble ... ]
;W[nh];B[qj];W[qi]
LB[rk:A][nh:5]
C[... after White 5 and 7. Next, White A is a deadly move. <= ]
))
)
(;
GM[1]
SZ[19]
AW[dd][cf][qc][qd][qf][rf][dp][dn][jq]
AB[fc][jd][pc][pd][pe][og][qh][fq][mq][pp]
TR[mq]
C[Problem 128. White to play.  

Black has just played the marked stone. What should White do ?  

[You will find a supplement to this Problem Diagram as "Problem 148"] ]
(;W[eq]
TE[2]
C[Correct Answer.  

White should attach with 1 and ... ]
;B[fp]
C[... Black will respond with 2. ]
;W[jo]
C[White now jumps out into the open with 3 ... ]
;B[gm];W[jm]
C[... and 5. Although White's stones don't have eye shape, neither do Black's. <= ]
)
(;W[fn]
C[Failure.  

White 1 is the wrong direction. ]
;B[ip]
C[Black plays the shoulder hit of 2 and ... ]
;W[jp];B[io];W[jo];B[in];W[km];B[il]
TR[mq]
C[... escapes into the center up to 8. Because of the marked stone, White's stones are a bit cramped. <= ]
)
(;W[hq]
C[Failure.  

White 1 is inefficient. ]
;B[cq]
C[Black invades the corner with 2 and ... ]
;W[dq];B[dr];W[er];B[cr];W[eq];B[bo]
LB[jo:A][hq:1]
C[... lives with the sequence to 8. White's stones are overconcentrated. The stone at 1 would be better placed at A. <= ]
)
(;W[dq]
C[Failure.  

Defending the corner with 1 loses a tempo. ]
;B[ip]
C[Black attacks with the shoulder hit of 2. ]
;W[jp];B[io];W[iq];B[gp];W[lp];B[kn];W[mp];B[nq]
C[The sequence to Black 10 leaves the white stones heavy. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ch][cg][dg][ef][ee][cd][co][od][ie][hd][hf][hg][ih][jf][kf][kg][lg][mg][mf]
AB[cb][ec][fd][fe][ff][eg][dh][di][ci][pp][qd][mc][me][le][ke][je][ld][lf][jc][ig][if]
TR[ih]
C[Problem 129. Black to play.  

White has just secured the center with the marked stone (White 16 in the Correct Answer of Problem 85). What should Black do next ? ]
;B[bd]
TE[2]
C[Correct Answer.  

Attaching with Black 1 is a severe attack on the white stones. ]
(;W[be];B[bc];W[cf];B[dd];W[de];B[bh];W[bg];B[bi];W[af]
C[White can live with the sequence to 10, but she ends in gote, while Black expands his corner territory and increases his influence facing down on the left side. <= ]
)
(;W[bc]
C[Variation.  

White can't resist with 2. ]
;B[be];W[cc];B[ce];W[de];B[bb];W[ad];B[dd]
C[The sequence to Black 9 will follow and the white stones are dead. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cd][bf][dc][fc][gb][hb][ic][cn][cq][dq][fq][pn][nn][ph][ng][li][ne][nd][nc]
AB[hc][hd][ie][fd][ed][df][dk][bn][co][dn][dp][pp][np][lp][lc][le][oc][pd][pf][re]
C[Problem 130. Black to play.  

This position arose from the Correct Answer in Problem 75. Where should Black attack ?  

[You will find a supplement to this Problem Diagram as "Problem 149"] ]
;B[qi]
TE[2]
C[Correct Answer.  

Black 1 is a severe invasion. ]
;W[qh];B[rh];W[rg];B[ri];W[qg];B[pi];W[oh];B[ql]
C[Black's aim is to drive a wedge between White's positions above and below with the sequence to 9. ]
;W[rn];B[om];W[on];B[nk];W[qq];B[qp];W[rp];B[ni]
C[Note Black 17. ]
(;W[lf]
C[White must defend with 18 ... ]
;B[ke];W[lg]
C[... and 20, inducing Black to strengthen his stones there. ]
;B[lk]
C[After Black 21, White's stones are without eyes in a sea of Black influence. <= ]
)
(;W[mh]
C[If White responds with 18 here, ]
;B[mf]
C[... Black will peep at 19, ... ]
;W[nf];B[nh]
LB[og:A][mg:B]
C[... then play 21. The points A and B are now miai, so White can't avoid losing some stones. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ec][dc][cd][bf][nb][nc][qc][pc][md][me][kf][lf][ke][kh][pr][nq][bp][cn][ck][li]
AB[df][ed][fc][gd][je][kd][lc][mc][qd][pd][od][nd][ji][mf][mg][pg][pj][pp][qn][cq][dp][fq]
TR[kh]
C[Problem 131. Black to play.  

How should Black attack after White played the marked stone (White 4 in then Correct Answer of Problem 47) ? ]
;B[lk]
TE[2]
C[Correct Answer.  

Black should cap with 1. ]
;W[jd]
C[White will play 2 ... ]
;B[jc];W[id]
C[... and 4 to get some aji at the top, ... ]
;B[ic];W[if];B[ie];W[jf];B[he];W[ih]
C[... then run away with the sequence to 10. ]
;B[ii]
C[Black forcefully drives White to the left side with 11 ... ]
;W[hh];B[gj];W[fh];B[ej];W[dh];B[cj]
C[... to 17, then, ... ]
;W[ch]
C[... when White links up to the corner with 18, ... ]
;B[bk]
C[... the white stones in the lower left suddenly find themselves in trouble. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cf][qc][qd][qf][rf][jq][jo][jm][jk][cn][dn][dp][eq]
AB[gc][jd][pc][pd][pe][og][qh][pp][qp][mq][gk][gm][dk][fq][fp]
LB[gk:A][dk:C][cn:D][jk:B][qp:E]
C[Problem 132. White to play.  

The game in Problem 128 continued with the sequence to Black E. What should White do now ? ]
;W[fl]
TE[2]
C[Correct Answer.  

White should peep with 1 ... ]
;B[gl];W[fn]
C[... and 3. ]
;B[ip]
C[After Black exchanges 4 ... ]
;W[jp]
C[... for 5, ... ]
;B[gn]
C[... Black has to defend with 6. ]
;W[ej]
C[White can now attack the black stone on the left with 7. Black's stones in the bottom left are in a pinch, while White is threatening to take all the territory on the left side. However, White's stones in the middle are not in any trouble because there is a lot of room in the center. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cf][kc][kd][kf][lg][qc][qd][qf][rf][kq][cq][dp][fq]
AB[fc][id][jc][jf][kg][pc][pd][pe][og][qh][pp][bp][cn][ck]
TR[lg]
C[Problem 133. Black to play.  

White has just played the marked stone (see Problem 57). How should Black counter this move ? ]
;B[ke]
TE[2]
C[Correct Answer.  

Black should atari at 1. ]
;W[le]
C[White has no choice but to block with 2. ]
;B[lf];W[mf];B[kf]
C[After Black connects with 5, ... ]
;W[ne];B[pf];W[md]
C[... the sequence to 8 is inevitable. ]
;B[lh];W[mg];B[mh];W[qb];B[nc];W[mc];B[ng]
C[Black now builds a wall in the center. ]
;W[nb]
C[White can live with her stones by playing 16, but Black ends in sente. Black's thick wall in the center gives him a huge advantage. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][cf][ne][ke][kc][qc][qd][qf][rf][cq][dp][fq][kq][lg][je][jg][kf]
AB[fc][jc][id][pd][pc][pe][pf][og][qh][bp][cn][ck][pp][li][jf][ie][if]
LB[je:A][jg:C][ie:B][if:D][kf:E]
TR[li]
C[Problem 134. Black to play.  

After Black caps with the marked stone (Black 7 in the Correct Answer to Problem 57), White plays the sequence to E. What should Black do ? ]
;B[kh]
TE[2]
C[Correct Answer.  

Peeping with 1 and ... ]
;W[kg];B[hh]
C[... jumping into the center with the knight's move of 3 is the best way to attack the white stones. ]
;W[mi];B[mh];W[lh];B[nh];W[ki];B[lj]
C[Black must not expect to kill these stones; instead, he should let them live and build a wall facing the right with the sequence to 9. ]
;W[ji]
C[White must play 10 in gote, ... ]
;B[db];W[cc];B[ch]
C[... giving Black the opportunity to play the big points of 13 ... ]
;W[cb];B[nq]
C[... and 15. <= ]
)
)
(;
GM[1]
SZ[19]
AW[cc][cd][de][dg][ch][rc][rd][qd][pc][oc][od][md][fc][hc][jd][je][ie][he][ge][hg][ih][ji]
AB[cb][dc][eb][ed][ee][ef][dp][pp][qb][qc][pd][pe][qe][kd][ke][jc][ic][id][gf][fh][jf][lf][kg][ij]
LB[ij:A][ji:B]
C[Problem 135. Black to play.  

When Black caps with A, White comes out diagonally with B. How should Black continue his attack ? ]
;B[kk]
TE[2]
C[Correct Answer.  

Exchanging Black 1 ... ]
;W[li]
C[... for White 2 is natural, ... ]
;B[nf]
C[... but Black 3 is a move that many players would miss. However, it is important because, if White were to play on this point, the black stones at the top would be separated. ]
(;W[mj]
C[White moves out with 4, ... ]
;B[pi]
C[... but Black attacks with 5. This move is also sente against the white stones in the corner, ... ]
(;W[rb]
C[... so White must defend with 6. ]
;B[ml]
C[Next, Black continues the attack with 7 ... ]
;W[oj];B[qk]
C[... and 9. The white stones are now in serious trouble. <= ]
)
(;W[ml]
TR[pi]
C[White dies.  

White wants to jump to 6 in answer to the marked stone, but if she does, ... ]
;B[rb]
C[... Black will turn at 7. ]
;W[re]
C[White fights back by cutting through with 8 ... ]
;B[rf];W[qf]
C[... and 10. but ... ]
;B[pf];W[qg];B[rg];W[pg];B[og];W[qh];B[rh];W[qi];B[qj];W[ri];B[rj]
C[... the white stones on the right are dead after the sequence to Black 21. <= ]
))
(;W[mk]
TR[nf]
C[Variation.  

In response to the marked stone, White might jump out into the center with the knight's move of 4. ]
;B[ni]
C[Black attacks with 5 ... ]
;W[mi];B[nj]
C[... and 7, ... ]
;W[lk];B[re]
C[... makes a sente move with 9, ... ]
;W[rb];B[ol]
C[... then stakes out territory on the right side with 11. ]
;W[kl];B[fj]
C[Black jumps out with 13, and ... ]
;W[jk]
C[... White secures her stones in the center with 14. ]
;B[cj]
C[Black now attacks the white group in the upper left with 15 ... ]
;W[bi];B[bj]
C[... and 17; ... ]
;W[df]
C[... White must defend in gote with 18. ]
;B[fq]
C[Finally, Black reinforces his corner with 19.  

In this attack, Black hasn't really gone all out for the kill. Instead, he has built up his territory on the right with moves that threaten White's stones. He gets the initiative on the left by attacking the white stones in the upper left. Black is now far ahead. This is a good example of the correct way to attack. <= ]
)
)
(;
GM[1]
SZ[19]
AW[fc][qn][qj][oc][nc][mc][md][me][le]
AB[dd][dp][cn][dj][pp][nq][pd][pc][nd][ne][pf][mf][kd][lb]
TR[le]
C[Problem 136. White to play.  

In Variation 1 of Problem 30, White extended with the marked stone. How should Black continue at the top ? ]
;B[gd]
TE[2]
C[Correct Answer.  

The shoulder hit of Black 1, a leaning attack, is a move that would not occur to many players, but, in this position, it is quite severe. <= ]
(;W[ee]
C[White tries to break out into the center with 2 ... ]
;B[de];W[ge]
C[... and 4, but ... ]
;B[he];W[gf];B[hf]
LB[he:5]
C[... Black plays 5 and 7. These last two moves attack the six white stones in the right, so ... ]
;W[lf]
C[... White must get into the center with 8. ]
;B[gc]
C[Black now takes the initiative on the left with 9 ... ]
;W[fd];B[gg]
C[... and 11. The white stones there are now in trouble. <= ]
)
(;W[fd]
C[If White pushes with 2 ... ]
;B[fe];W[ee]
C[... and 4, ... ]
;B[ff]
C[... Black extends to 5. ]
;W[ed]
C[After White connects with 6, ]
;B[kg]
C[... Black attacks the stones on the right with 7. ]
;W[ke];B[jd];W[je];B[id];W[jg];B[jh];W[ig];B[ie];W[if];B[kh];W[ih]
C[White manages to get out into the center with the sequence to 18, but ... ]
;B[dc]
C[... Black switches back to the left and ... ]
;W[de];B[be];W[bf];B[bd];W[dg];B[fh]
C[... traps the white stones with the sequence to 25. White is unable to live. <= ]
)
)
(;
GM[1]
SZ[19]
AW[db][eb][ed][fd][gd][lc][qi][pm][qn][po][dp][dj]
AB[cb][bc][dc][dd][ee][fe][gc][nc][pd][qd][qo][qp][pq][nq][qg]
TR[qg]
C[Supplement to Problem 13: The joseki.  

When the marked stone is in place, ... ]
;B[ql]
TE[2]
C[... Black 1 is the start of a middle-game joseki (See Get Strong at Invading, Problems 27, 30, 33, 36, 39, and 42.). ]
;W[rm]
C[After White 2, ... ]
;B[pj]
LB[rj:A]
C[... Black 3 or A are joseki moves. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][nq][kq][ko][eq][dp][dn]
AB[pd][oo][qo][pq][iq][fq][fp]
LB[pi:A]
C[Supplement to Problem 23: Correct for Black.  

Instead of playing at A in the Problem Diagram, ... ]
;B[io]
TE[2]
C[... Black should have reinforced his stones at the bottom with 1. ]
(;W[mo]
C[Now it is White who must defend with 2. Next, ... ]
;B[pi]
C[... Black can extend to 3. <= ]
)
(;W[ck]
LB[mo:@]
C[If White omits @ and extends to 2, ... ]
;B[lp]
C[... Black will attack White's stones at 3 ... ]
;W[kp];B[mr]
C[... and 5. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dp][dn][hp][iq][hq][jq][lq][qi]
AB[fq][fo][go][ho][ip][jp][kp][mo][pp][pd]
LB[cj:A]
C[Supplement to Problem 25: White's best move.  

Instead extending to A in the Problem Diagram, ... ]
;W[nq]
LB[mq:A]

TE[2]
C[... White should have jumped to 1. Her stones are now secure. Many joseki books give only the extension to White A as the next move, but 1 here is preferred because it aims at the outside. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][ec][df][dp][jq][jd][jg]
AB[pq][po][pd][md][fc][fd][gg]
LB[pj:A]
C[Supplement to Problem 45: Black's mistake.  

Instead of extending to A, ... ]
;B[hd]
TE[2]
C[... Black should have played 1. It is now White who has to make shape for her stones. ]
;W[le]
C[White 2 ... ]
;B[me];W[lf]
C[... and 4 are the usual way to do so, but ... ]
;B[ng]
LB[me:3]
C[... these moves provoke 3 and 5, enabling Black to begin building a moyo in the upper right. <= ]
)
)
(;
GM[1]
SZ[19]
AW[fc][gd][ge][fe][cn][en][bp][pp][pd][pf]
AB[dd][ed][ec][fd][df][dk][dp][cq][fq][nc][kd]
LB[qj:A]
C[Supplement to Problem 71: White's best move.  

Instead of playing A as in the Problem Diagram, ... ]
;W[bk]
TE[2]
C[... White should have slid to 1. This is the joseki move and it cannot be omitted. White's stones are settled and the territory on the left side is up for grabs. ]
;B[qk];W[qi];B[qn];W[qo];B[pn];W[nq]
C[The game would most likely continue with the sequence to 7. <= ]
)
)
(;
GM[1]
SZ[19]
AW[fc][cm][dm][em][fm][fn][bn][bo][cp][cq][dq][dr][po][pp][pq][oq][or][lq][oc][pe][id][jc]
AB[dd][cf][dj][ck][co][cn][dn][dp][ep][eo][en][fq][bp][bq][br][cr][qr][pr][qq][qp][qn][nq][kc]
LB[kd:C][jc:B][kc:A]
C[Supplement to Problem 87: Black's best response.  

Instead of playing C in the Problem Diagram, ]
;B[ke]
TE[2]
C[... Black should have jumped lightly to 1. The black stones are now out in the open and Black has a good game. <= ]
)
)
(;
GM[1]
SZ[19]
AW[qf][pj][pp][jq][jo][cq][dq][er][cj][cm]
AB[cd][ec][pd][nc][dp][cp][ep][gq][ho][ch]
C[Supplement to Problem 94: Another example.  

Here is a similar position. ]
;B[em]
TE[2]
C[Black 1 reinforces his weak stones below while attacking the white stones on the left side. ]
;W[ej];B[dk];W[ck];B[eh]
C[Black jumps to 5 and, ... ]
;W[dl]
C[... when White reinforces with 6, ... ]
;B[id]
C[... expands his moyo with 7. <= ]
)
)
(;
GM[1]
SZ[19]
AW[ec][ed][qq][pq][op][kq][cp][dp][dn][ep][fp][eq][gq][hq][bh][ci][cg][dg][ef]
AB[dc][cd][ic][pd][pm][qp][ro][rq][fq][gp][fo][fr][er][dr][cq][df][cf][bf][bg]
LB[gh:E][di:D][eh:C][ff:B][eg:A]
C[Supplement to Problem 100: The best way for Black.  

Instead of cutting at A in the Problem Diagram, ... ]
;B[if]
TE[2]
C[... Black should have simply jumped to 1. ]
;W[eg]
C[Connecting at White 2 in now necessary. ]
;B[md]
C[Black can then stake out his own moyo in the upper right with 3. <= ]
)
)
(;
GM[1]
SZ[19]
AW[de][cf][dg][ck][jq][pq][np][nn][pl][pc][qd]
AB[dc][fc][cd][ce][cp][eq][om][pn][qo][rq][qi][qf]
LB[kc:A]
C[Supplement to Problem 106: White's best move.  

Instead of extending to A in the Problem Diagram, ... ]
;W[pj]
TE[2]
C[... White should have played a shoulder hit at 1. ]
;B[pi];W[oj]
C[She could then move out into the center with 3 ... ]
;B[nh];W[mj]
LB[cn:B][kc:A]
C[... and 5. Depending on how Black plays next, White can aim at the points A and B. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dc][dq][cn][nc][pb][qb][qc][qd][qf]
AB[eb][fd][de][pp][pd][pe][pc][oc][ob]
LB[be:A]
C[Supplement to Problem 113: Black's best move.  

Instead of playing at A, ... ]
;B[nd]
TE[2]
C[... Black should have made good shape with 1, Black now has a dominant position at the top. <= ]
)
)
(;
GM[1]
SZ[19]
AW[bb][cb][db][dc][ed][fc][dh][cl][cr][dq][eq][gq][jq][qj]
AB[cc][bc][ad][be][ce][de][dd][df][ec][bq][cq][dp][co][fo][oq][qp][pd]
LB[nc:A][qf:B][qm:C]
C[Supplement to Problem 120: White's best move.  

Instead of A and C in the Problem Diagram, ... ]
;W[bg]
TE[2]
C[... White should have played 1. This move threatens the eye shape of the black stones above, so if Black invades on the left side, the fighting could spill over the top and the black stones there could get into trouble. For that reason, White 1 is a good move because it reinforces her thin stones on the left. <= ]
)
)
(;
GM[1]
SZ[19]
AW[dd][dc][df][ch][bg][co][dp][gq][jq][rp][rn][sn][sm][qm][ql][rl][qk][qj][pj][qi][ri][qh][qd][rd]
AW[qa][pa][pb][pc][oc][od][oe][mb][mc][lc][kc][kd][kb][jb][hb][hj][nk][gk][hk][cr][dq][hp]
AW[ho][cn][dm][cl][dl]
AB[bh][cj][cm][oq][qp][qn][qo][ro][so][rh][sg][rf][re][qe][pe][pd][qc][rc][qb][ra][ne][nf]
AB[md][ld][nb][ib][ic][jc][jd][je][ke][fc][fe][gi][pk][ok][oj][ol][pi][ph][gj][dr][eq][fp]
AB[gp][fn][dn][hm][em][jm][fk]
LB[jm:A]
C[Supplement to Problem 123. ]
)
)
(;
GM[1]
SZ[19]
AW[cd][dc][fc][gb][hb][ic][cn][cq][dq][fq][pn][nn][ph][ng][li][ne][nd][nc]
AB[hc][hd][ie][fd][ed][df][dk][bn][co][dn][dp][pp][np][lp][lc][le][oc][pd][pf][re]
LB[bf:A]
C[Supplement to Problem 130: A big move.  

The stone at A in the Problem Diagram is a big move because it expands White's corner territory while denying Black significant territory on the left side. If White omits it, ... ]
;B[ce]
TE[2]
C[... Black can  secure most of the territory on the left side ... ]
;W[bd];B[ec];W[eb];B[dd]
C[... and make good shape with the sequence to 5, ... ]
;W[cb]
C[... ending in sente. <= ]
)
)