(;
GM[1]
SZ[19]
AW[de][dc][rd][qf][qi][nq][np][jp][jq][iq][fq][cn][cp][cq][cr][dr][ql][bc][cd][qo][ro][qq][en][em][cm]
AB[dp][pd][pp][jc][nd][qc][qn][oq][ip][hp][hq][eq][er][dq][do][cg][cj][gc][bd][be][pr][po][fp][cl][bl][dl]
LB[bl:1][dl:3][em:2][en:4][fp:5][qq:6][pr:7][qo:8][po:9][ro:10]
C[Problem 165. Black to play.  

After the sequence to Black 5 was played, White invaded the corner with 6. How should Black continue after White 10 ? ]
(;B[no]
LB[pn:B][rn:A]

TE[2]
C[Correct Answer.  

Black wants to block at A, but then White would cut at B. Therefore, Black leans on the white stones on the left by attaching with 1. ]
;W[mo]
C[If White 2, ... ]
;B[nn]
LB[pn:A]
C[... Black extends to 3. Now his defect at A is covered, so ... ]
;W[rn]
C[... White must turn at 4. ]
;B[mn]
C[Next, Black turns at 5 and attacks the white stones below ... ]
;W[lo];B[nr];W[mr];B[ln];W[kn];B[km]
C[... with the sequence to 11. ]
;W[jn];B[ok]
C[Finally, Black plays 13 and establishes a strong position in the center. <= ]
)
(;B[pn]
C[How the game continued.  

Black connected at 1, so ... ]
;W[rn]
C[... White turned at 2. ]
;B[nr]
C[After exchanging 3 ... ]
;W[mr]
C[... for White 4, ... ]
;B[nn]
C[... Black jumped to 5. ]
;W[ns]
C[White exchanged 6 ... ]
;B[or]
C[... for Black 7, ... ]
;W[jn]
C[... then jumped to 8. Now, instead of White being under attack as in the Correct Answer, the black stones on the right, and even the ones on the left, were under attack. The sequence in the Correct Answer is a good example of a leaning attack. That is, instead of defending a weak point directly, Black defended it by attacking another group. <= ]
)
)