(;
GM[1]
SZ[19]
AW[cd][fc][nc][nb][pc][qc][qm][ro][qq][nq][mp][iq]
AB[dp][pp][lc][me][qd][pd][od][pj][oq][np][mq][no][dn][ci]
LB[cd:1][fc:11][lc:4][me:10][nb:9][nc:3][od:8][qc:5][qd:6][pc:7]
LB[pj:2][qm:21][ro:19][qq:17][oq:18][mq:20][np:14][no:16][mp:15][nq:13]
LB[iq:23][ci:12][dn:22]
C[Problem 152. Black to play.  

In this three-stone handicap game, White invades the bottom with 23. How should Black respond ? ]
(;B[gq]
TE[2]
C[Correct Answer.  

Black should make the checking extension of 1, ... ]
(;W[kq]
C[... forcing White to extend to 2. ]
;B[qp]
C[Black next plays the forcing sequence ... ]
;W[rp];B[qr];W[rr];B[pq]
C[... to 7, to give his stones on the right breathing room in case they get into trouble, ... ]
;W[rq];B[ho]
C[... then attacks White's group at the bottom with 9. <= ]
)
(;W[io]
C[Variation.  

If White jumps to 2, ... ]
;B[im]
C[... the cap of Black 3 is an interesting move. ]
;W[go]
C[If White tries to escape with 4, ... ]
;B[eq]
C[... Black will secure the territory at the bottom with 5. <= ]
))
(;B[kq]
C[How the game continued.  

Not only was Black 1 too narrow an extension, it was also the wrong direction. ]
;W[fq]
C[White was able to stabilise her stones at the bottom with 2 ... ]
;B[eq];W[fp]
C[... and 4. <= ]
)
)