(;
GM[1]
SZ[19]
AW[dd][fm][en][dn][co][cp][bq][gp][qn][qk][nc][kc]
AB[cf][di][dl][cq][dp][eo][fo][eq][pq][qp][qi][qf][pd]
TR[cf]
C[Problem 64. White to play.  

Black has just played the marked stone. How should White respond ? ]
(;W[cr]
TE[2]
C[Correct Answer.  

The atari of White 1 robs the black stones of their base. ]
;B[go]
C[Black has to run away ... ]
;W[ip];B[ho]
LB[go:2]
C[... with 2 and 4, but ... ]
;W[lq]
LB[ip:3]
C[... these moves provoke 3 and 5, enabling White to establish a position at the bottom. <= ]
)
(;W[fd]
TR[cf]
C[Failure.  

In the game, White answered the marked stone with 1. ]
;B[cr]
C[Black descended to 2, securing his stones in the lower left. Black has a good game because all of his stones are secure. <= ]
)
)