(;
GM[1]
SZ[19]
AW[jc][nc][pb]
AB[dd][gc][pd][qc][pf]
C[Problem 31. Black to play.  

The white stones are overextended. Black has to attack now. How should he play ? ]
;B[lc]
TE[2]
C[Correct Answer.  

Black 1 is the invasion point. This urgent move takes priority over all others. ]
;W[lb]
C[If White attaches with 2, ... ]
;B[kb];W[kc];B[mb]
LB[kb:3]
C[... Black plays 3 and 5. ]
;W[ld]
C[White tries to link up with 6 to ... ]
;B[mc];W[md];B[nb];W[oc]
C[... 10, but ... ]
;B[nd]
C[... Black cuts with 11, catching three white stones. <= ]
)
)