(;
GM[1]
SZ[19]
AW[dd][cc][fd][qf][qi][po][qn][pm][cq][do]
AB[hc][oc][qd][qo][qp][pq][nq][cf][bd][ci]
C[Problem 175. Black to play.  

There are a lot of points that Black might play, but he should focus on strengthening his position at the top. Where should he play ? ]
(;B[oe]
TE[2]
C[Correct Answer.  

Black 1 is the best point in this position, since it prevents White from expanding his own position on the right. ]
(;W[kd]
C[Next, if White invades at 2, ... ]
;B[he]
LB[kd:2]
C[... Black will jump to 3 and the white stones on the left, as well as the one at 2, will come under attack. <= ]
)
(;W[he]
LB[ph:C][qg:B][pg:A][oe:1]
C[Continuation.  

One of the aims of Black 1 is to build influence with the sequence Black A - White B - Black C, so it is not a good idea for White to invade at the top. Therefore, she might exchange 2 ... ]
;B[jd]
C[... for 3, ... ]
;W[ck]
C[... then extend to 4. ]
;B[hp]
C[Black would then take the last extension at 5. <= ]
))
(;B[kd]
C[Failure.  

Black 1 is a rather dull move. ]
;W[oe]
C[White expands her moyo on the right while flattening Black with 2. ]
;B[nd];W[hd]
C[She then defends her stones on the left with 4 ... ]
;B[id];W[gc]
LB[kd:1]
C[... and 6. Black 1 thinks only of defending his territory at the top. <= ]
)
(;B[he]
C[Failure.  

Black 1 also misses the point. ]
;W[df]
C[White first forces with 2 to make sure that her stones on the left can escape, ... ]
;B[cg];W[oe]
C[... then plays the vital point of 4. <= ]
)
(;B[iq]
C[Failure.  

The top is most important in this position. If Black plays at the bottom with 1, ... ]
;W[oe];B[nd];W[ne];B[me];W[mf];B[md];W[lf];B[kd];W[mn]
C[... White will expand her moyo on the right side with the sequence to 10. <= ]
)
)