(;
GM[1]
SZ[19]
AW[dd][df][cj][dp][jq][nq]
AB[pp][qn][pd][pf][fc][jc]
C[Problem 69. Black to play.  

Each side has staked out his sphere of influence. However, Black must now invade White's moyo. Where should he play ? ]
(;B[cq]
LB[jo:A][ej:A]
TR[jq][cj]

TE[2]
C[Correct Answer.  

Black should invade the lower left corner with 1. Since both the marked stones are on the third line, White can't expect to make a large-scale moyo because Black can cap at one of the points marked A. ]
(;W[dq]
C[If White blocks with 2 and ... ]
;B[cp];W[co];B[bo];W[cn];B[bn];W[cm];B[dr];W[er];B[cr];W[fq]
C[... plays the sequence to 12, ... ]
;B[no]
C[... Black will cap at 13 to build his own moyo on the right and prevent White from making one herself. <= ]
)
(;W[cp]
C[Variation.  

White could also block from the other side with 2. ]
;B[dq];W[eq];B[er];W[fq];B[fr];W[gq];B[bp];W[bo];B[bq];W[cn];B[gf]
LB[jo:B][ej:B][ge:A]
C[This time, however, Black will map out his moyo at the top with 13. This move also neutralises White's thickness below. If Black omits this move, White will map out a large-scale moyo by playing at A. After 13, Black still has the capping moves at the points B. <= ]
))
(;B[pj]
C[Failure.  

If Black continues to map out his own territory by taking the big point at 1, ... ]
;W[fp]
LB[dn:A]
C[... White will defend her position with 2 (or A) and Black will have a harder time erasing White's moyo. That is not to say that Black has a bad position, but he has lost his chance to decisively take the lead. <= ]
)
)