(;
GM[1]
SZ[19]
AW[jd][nc][ql][qn][dm][ck][cj][ch]
AB[pj][dj][dp][pd][pp][dd][gc][pf][qj][jp][gp][fj][dk]
TR[qn]
C[Problem 86. Black to play.  

White extends with the marked stone to establish a position on the lower right side. How should Black attack these two stones ? ]
(;B[qo]
TE[2]
C[Correct Answer.  

Black should attach with 1 ... ]
;W[pn]
C[... to induce White to defend with 2. ]
;B[np]
C[Black will the defend the bottom with 3. ]
;W[qq]
C[White can't wrest the corner from Black by invading at 4 because ... ]
;B[ro]
LB[ol:A]
C[... Black will answer at 5, after which Black A is too severe for White to allow, so the territory in the corner should become Black's. <= ]
)
(;B[nq]
C[How the game continued.  

Black 1 was a timid move. ]
;W[rp]
C[White slid to 2 and there was no longer an attack on the white stones. ]
;B[qq]
C[Even if Black had answered with 3, White could easily have made eyes for her stones on the lower right, so she could have played elsewhere. White could now fight for what had previously been Black's territory. <= ]
)
)