(;
GM[1]
SZ[19]
AW[cd][dc][ec][bf][kd][ld][nc][ne][ql][qn][rp][cn]
AB[df][ed][fd][fc][jc][kc][lc][pd][pf][qj][qq][pp][np][dp]
TR[kd][ld][nc][ne]
C[Problem 46. Black to play.  

How should Black attack the four marked white stones ? ]
(;B[lf]
LB[md:A]

TE[2]
C[Correct Answer.  

Black 1 blocks White's escape route into the center and aims at A. ]
(;W[md]
C[If White defends there, ... ]
;B[ng]
C[... Black continues the attack with 3. <= ]
)
(;W[mf]
C[If White attaches with 2, ... ]
;B[md]
C[... Black hanes at the vital point with 3. ]
;W[mc];B[le];W[me]
LB[md:3]
C[White captures the stone at 3 with 6, but ... ]
;B[je]
C[... Black casts a net with 7, making a thick position facing the left. White's stones are still without eye shape. <= ]
))
(;B[pb]
C[Failure.  

Defending the corner with 1 is passive. ]
;W[kg]
C[White can gingerly jump out into the center with 2. <= ]
)
)