(;
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. <= ]
))
)