(;
GM[1]
SZ[19]
AW[qf][pj][qn]
AB[dp][pd][pp][dd][jj][nd][np]
LB[qf:1][nd:2][qn:3][np:4][pj:5]
C[Problem 91. Black to play.  

White has mapped out a sphere of influence on the right side with the sequence to 5. What should Black do next ? ]
(;B[dj]
TE[2]
C[Correct Answer.  

Black should map out his own sphere of influence on the left side. This works well with Black's handicap stones and Black is well ahead. ]
;W[fq]
C[If White continues with 2 ... ]
;B[dn];W[lq]
C[... and 4 at the bottom, ... ]
;B[jd]
C[... Black will take another big point with 5 at the top. Next, ... ]
;W[fc]
C[... White invades Black's box-shaped moyo with 6 and ... ]
;B[ec];W[fd];B[df];W[hd]
LB[fd:8]
C[... tries to build a base there with 8 and 10. ]
;B[gg];W[hf];B[hg]
C[Black attacks with the sequence to 13, ... ]
;W[jf];B[ld]
C[... then secures the territory at the top with 15. ]
;W[ig];B[hi]
C[After 17, Black's moyo in the upper left is nearly impregnable. White's stones at the top, however, are still not secure. Black has taken a big lead. <= ]
)
(;B[rd]
C[How the game continued.  

Defending the corner with  Black 1 was not urgent and didn't take the whole board into account. Even though White's framework on the right was threatened, ... ]
;W[lq]
C[... White played quickly and established a presence in virgin territory. This is an important principle for White to follow in handicap games: 'If Black plays a lukewarm move, ignore it and play elsewhere.' <= ]
)
)