(;
GM[1]
SZ[19]
AW[dc][cp]
AB[pp][pd]
LB[pd:1][dc:2][cp:4][pp:3]
C[Problem 37. Black to play.  

When White makes this komoku formation on the left side with 2 and 4, from which side should Black approach ? ]
;B[ep]
TE[2]
C[Correct Answer.  

The high approach of Black 1 in the lower left corner works best with Black's niren-sei formation on the right. ]
;W[eq];B[fq];W[dq]
(;B[fp];W[cn]
C[If the joseki to White 6 is played, ... ]
;B[jp]
LB[pj:B][de:A]
C[... Black makes an ideal extension to 7 at the bottom. A corner enclosure at White A would now seem natural, but Black would make a sanren-sei with B, so ... ]
;W[qn]
C[... White plays 8 to prevent this. ]
;B[ql];W[qq];B[pq];W[qp];B[po];W[rn];B[om]
C[Still, Black gets a moyo at the bottom when he plays 15. <= ]
)
(;B[gp]
C[Variation.  

In this game, White answered Black 5 ... ]
;W[dn]
C[... with 6, so ... ]
;B[pj]
C[... Black switched to the right side, making a sanren-sei with 7. ]
;W[nq]
C[White then approaches with 8, but ... ]
;B[lq]
C[... Black 9 became an ideal move, being both a pincer and an extension from his stones on the left. <= ]
)
)
