(;
GM[1]
SZ[19]
AW[nc][dm][cf][hc][cd][bc][de][be][ch]
AB[pj][dj][dp][pd][pp][dd][pf][fp][fd][dg][cc][bb][ed][ac]
LB[nc:1][pf:2][dm:3][fp:4][cf:5][fd:6][hc:7][dg:8][cd:9][cc:10]
LB[bc:11][bb:12][de:13][ed:14][be:15][ac:16][ch:17]
C[Problem 73. Black to play.  

When Black ataris with 16, White doesn't connect but jumps lightly to 17. How should Black respond ? ]
(;B[kc]
TE[2]
C[Correct Answer.  

Black is strong on the left and the right, so he should make a deep invasion at 1, separating the weak white stones at the top. ]
;W[he]
C[If White jumps to 2, ... ]
;B[oc]
C[... Black exchanged 3 ... ]
;W[nd]
C[... for 4, ... ]
;B[ke]
C[... then jumps to 5. White has now weak groups on the left and the right. It will be difficult for her to save both of them. Black has a won game. <= ]
)
(;B[kd]
C[How the game continued.  

Black 1 was also an invasion, but it lacked the severity of the one in the Correct Answer. ]
;W[kb]
LB[kd:1]
C[White slid to 2 and her stones on the left and the right were able to link up.  

Black 1 was a light move, and such moves are played when it is important to escape quickly. It would be appropriate if White hat had strong positions at the top. However, White was weak and Black was strong. Since Black had nothing to fear, the high invasion of Black 1 was inappropriate. See Problem 77 for the continuation. <= ]
)
)