(;
GM[1]
SZ[19]
AW[cd][ed][hc][ch][qc][oc][nb][qf][pf][qi]
AB[jc][cj][nc][nd][od][pd][qe][re]
LB[nc:2][nb:1]
C[Problem 131. White to play.  

Against White 1, Black 2 is a strong move. How does White live ? ]
(;W[ob]
TE[2]
C[Correct Answer.  

Connecting at 1 is the proper move. ]
;B[mb]
C[After Black blocks with 2, ... ]
;W[rb]
C[White lives with 3. <= ]
)
(;W[pc]
C[Failure.  

Connecting at 1 is bad. ]
;B[mb]
(;W[ob]
C[After White 3, ... ]
;B[sb]
C[... Black kills her with 4. <= ]
)
(;W[rb]
C[If White 3 here, she lives, but ... ]
;B[ob]
C[... Black can capture a stone in sente with 4. <= ]
))
)