(;
GM[1]
SZ[19]
AW[ch][cd][ed][hc][qc][qf][pf][qi]
AB[cj][jc][nd][pd][qe][re]
LB[re:1]
TR[qc]
C[Problem 125. White to play.  

Black 1 is a strong response to the invasion by the marked stone. Black intends to give White the corner and attack the right side. What is White's next move ? ]
(;W[oc]
LB[ob:A]

TE[2]
C[Correct Answer.  

Peeping at White 1 is a tesuji. As you will see in the Failure Diagram, White 1 at A is not good. <= ]
)
(;W[ob]
C[Failure. ]
;B[oc]
LB[ob:1]
C[Black 2 is a good response to White 1. ]
(;W[nb]
C[If White 3, ... ]
;B[pb]
C[... Black plays 4 and takes the corner. <= ]
)
(;W[pb]
C[If White draws back to 3, ... ]
;B[nb]
C[... Black blocks at 4. ]
;W[rb]
C[White gets a small life. White's result is bad. <= ]
))
)