(;
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. <= ]
)
)