(;
GM[1]
SZ[19]
AW[dc][fc][hc][dh][dm][dp][po]
AB[he][fe][de][dk][pq][pl][pd]
LB[dk:A][dm:B]
C[Problem 70.  Black to play.  

The exchange of Black A for White B has taken place on the left. How should Black continue ? ]
(;B[cc]
TE[2]
C[Correct Answer.  

Black should attach with 1, ... ]
;W[cb];B[dd]
C[... then reinforce his position by forcing with 3. ]
;W[ec]
C[White must answer with 4. ]
;B[ei]
C[Black can now use his thick position above to attack the white stone with 5. ]
)
(;B[ei]
LB[ec:D][dd:C][cb:B][cc:A]
C[Failure.  

If Black attacks at 1 without reinforcing as in the Correct Answer (A and C), ... ]
;W[ce]
C[... White can attach and cut with 2 ... ]
;B[cf];W[df]
C[... and 4, then ... ]
(;B[cd];W[ee];B[be];W[ef]
C[... link up with the sequence to 8. <= ]
)
(;B[fh]
C[Failure.  

Simply capping with 1 and ... ]
;W[ei]
(;B[gj]
C[... playing the knight's move of 3 just enables White to get the initiative on the left side ... ]
;W[ek]
LB[ei:2]
C[... with 2 and 4. The black stone on the left side still has some aji, but Black is now at a serious disadvantage there. ]
)
(;B[fk]
LB[ei:2][fh:1]
C[After exchanging 1 for White 2, Black could jump to 3. ]
;W[fi];B[gi];W[gh];B[gj];W[fg];B[hh];W[gg];B[hg]
C[Black confines White to the left side with the sequence to 11. This is a reasonable result, but not as good as the one in the Correct Answer. <= ]
))
(;B[ef]
TR[df]
C[Variation.  

When White cuts with the marked stone, Black can't get a good result with the atari of 5 here. ]
;W[dg];B[cd];W[be];B[dd];W[di];B[ej];W[bd];B[cc]
LB[jd:B][db:A]
C[After the sequence to Black 13, White's stones on the left are alive and she can secure her stones at the top by playing A or B. <= ]
))
)