(;
GM[1]
SZ[19]
AW[dd][dj][dp][jp][kd][nc][qg][qf][qd][qc][qb][pb]
AB[id][ob][oc][pc][nd][pd][pe][pg][ph][pj][lp][pp]
TR[kd]
C[Problem 19. Black to play.  

How should Black attack the marked white stone ? ]
(;B[jf]
TE[2]
C[Correct Answer.  

Black should play the knight's move of 1. ]
;W[lf]
C[If White runs away with 2, ... ]
;B[kh]
TR[pj][ph][pg][pe][pd][pc][ob][oc][nd]
C[... Black drives White into his marked stones with 3. White's stones are lost. <= ]
)
(;B[kf]
C[Failure.  

Capping with Black 1 is a terrible move. ]
;W[je]
C[White moves out into the center with the diagonal move of 2. ]
;B[ig]
C[If Black 3, ... ]
;W[ie]
TR[id]
C[... White plays 4 and neutralises the marked stone. Black has suffered a big loss. <= ]
)
)