(;
GM[1]
SZ[19]
AW[dc][ce][ch][jc][mc][oc]
AB[cj][qc][qf]
C[Problem 157. Black to play.  

What is the best way to reduce White's moyo on the upper right ? Is a deep or shallow invasion called for ? ]
(;B[id]
TE[2]
C[Correct Answer.  

The shoulder hit of Black 1 is the best move. A deeper invasion would be dangerous. ]
(;W[ic];B[hd];W[ke];B[ig]
C[After Black jumps out to 5, he has nothing to worry about. One thing you must remember when you make a shoulder hit: expect to end in gote.  <= ]
)
(;W[jd]
C[Variation.  

White could also push up with 2, ... ]
;B[ie]
(;W[hb]
C[... then slide to 4. ]
;B[je]
C[White gets profit, while Black gets influence.  <= ]
)
(;W[je]
C[If White 4 here, ... ]
;B[if]
C[... Black would play at 5.  <= ]
)))
(;B[ie]
C[Failure.  

Erasing White's moyo with Black 1 ... ]
;W[hd]
C[... induces White to play 2, which is ideally placed in relation to her other stones.  <= ]
)
(;B[ee]
C[Failure.  

Capping with Black 1 is also dubious. ]
;W[fd]
C[Again, White 2 is an ideal point.  <= ]
)
(;B[hc]
C[Failure.  

Because White's three stones at the top right are so strong, invading at Black 1 is foolish.  

<See Reference Diagram 157 for a situation where Black 1 might be playable.> ]
;W[fc]
C[White attacks with 2 ... ]
;B[he];W[je]
C[... and 4, and all Black can do is escape with this stones. <= ]
)
)