(;
GM[1]
SZ[19]
AW[md][eb][fc][gd][eg][ch]
AB[dp][pd][pp][dd][pg][df][fd][fe][ck]
LB[ck:6][ch:5][eg:7][df:4][fd:8][fe:10][eb:11][fc:3][gd:9][md:1]
LB[pg:2]
C[Problem 109. Black to play.  

After White plays the diagonal move of 11, how should Black secure his stones in the corner ? ]
(;B[db]
TE[2]
C[Correct Answer.  

Black should attach at 1 and ... ]
;W[dc];B[cc];W[ec];B[cb]
LB[ic:A]
C[... the sequence to 5 will inevitably follow. White's stones at the top are heavy and Black is threatening to pincer at A, so ... ]
;W[ic]
C[... White must take this point herself with 6. ]
;B[cf]
LB[ej:B][di:A]
C[Next, Black secures the corner with 7, robbing White's stones on he left of a base. Next, Black A would be a strong attack against these stones, so White has to defend with a move around B. <= ]
)
(;B[cc]
LB[bf:A]
C[How the game continued.  

Black 1 also secured the corner, but the situation there is still undefined and White's stones at the top were light and flexible. In addition, the possibility of White A was an annoyance to Black. ]
;W[dn]
C[Since the two white stones in the upper left were in no immediate danger, White made an approach at 2, preparing to attack the black stone on the left side. <= ]
)
)