(;
GM[1]
SZ[19]
AW[dg][cl][cn][dn][en][fn][gn][hm][il][fj]
AB[jp][jd][pj][dj][dp][pd][pp][dd][fd][dm][em][fm][gm][fp][gp][hl][hk][jj]
LB[fd:4][dg:3][fj:5][cn:1][fp:2][gp:14][dn:7][en:9][fn:11][gn:13]
LB[hm:15][il:17][cl:19][dm:6][em:8][fm:10][gm:12][hl:16][hk:18]
C[Problem 34. Black to play.  

In this nine-stone game, Black played the sequence to 18. How should he respond to White 19 ? ]
(;B[ek]
TE[2]
C[Correct Answer.  

Black should play the diagonal move of 1, not only to strengthen his stones but also to isolate the two white ones in the upper left from their allies below. ]
;W[in]
C[White comes back to defend with 2, ... ]
;B[ik]
LB[ci:B][bj:A]
C[... and Black turns at 3, building a huge moyo in the upper left. If White A, Black will calmly give way with B. <= ]
)
(;B[ej]
C[How the game continued.  

Black 1 was a good move, but ... ]
;W[fk]
C[... answering the peep of White 2 ... ]
;B[gl]
LB[fi:A]
C[... with 3 was cowardly. Black should have haned at A instead. ]
;W[dl];B[fi]
C[Now when Black cut at 5, ... ]
;W[ei]
C[... White crosscut with 6 ... ]
;B[gi];W[di]
C[... and the black stones on the left side became separated from their allies above. ]
;B[cj];W[ek]
C[With 10, White took a big piece of territory on the left side. <= ]
)
)