(;
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. <= ]
)
)