(;
GM[1]
SZ[19]
AW[ce][fe][cn][pq][mq][qo]
AB[dc][gc][ch][dp][jq][qd]
TR[cn]
C[Problem 109. Black to play.  

The marked white stone on the left is outnumbered. How should Black attack it ? ]
(;B[co]
TE[2]
C[Correct Answer.  

Black should make a diagonal attachment with 1. ]
;W[dn]
LB[fp:A]
C[White will stand at 2, but instead of jumping to A, ... ]
;B[ck]
C[... Black will pincer with 3. The two white stones are now heavy and under attack. ]
;W[ep]
C[If White attaches with 4, ... ]
;B[eq]
C[... after the exchange of Black 5 ... ]
;W[fp]
C[... for White 6, ... ]
;B[do]
C[... Black 7 is the vital point. ]
;W[en]
C[After White 8, ... ]
;B[dq]
C[... Black secures his stones in the corner with 9. <= ]
)
(;B[fp]
C[Failure.  

If Black jumps to 1, ... ]
;W[ck]
TR[ch]
C[... White plays the checking extension of 2, so Black's marked stone comes under attack. <= ]
)
)