(;
GM[1]
SZ[19]
AW[ch][jc][lc][pc][pd][qe][qf]
AB[dc][cf][hc][nc][pb][pe]
LB[pd:2][pb:1]
C[Problem 91. Black to play.  

What does Black do if White answers 1with 2 ? ]
(;B[qb]
TE[2]
C[Correct Answer.  

Wrenching the corner territory away from White with 1 is the natural move. ]
;W[nd]
C[Next, White attaches with 2. ]
;B[oc];W[od];B[rd]
C[Black's invasion is a success. <= ]
)
(;B[ob]
C[Failure.  

If Black draws back with 1, ... ]
;W[qb]
C[... White takes the corner with 2 and Black's shape has been destroyed. <= ]
)
)