(;
GM[1]
SZ[19]
AW[dd][fc][co][cp][dq][fq][nc][nb][pc][qc][rc]
AB[cf][dj][cn][do][dn][pp][pj][pd][qd][od][nd][lc]
C[Problem 156. White to play.  

Black has made a moyo on the right with his sanren-sei formation, but there is still a weak point in his position. Where should White play next ? ]
(;W[md]
TE[2]
C[Correct Answer.  

Cutting through the black position with 1 ... ]
;B[mc];W[me]
C[... and 3 is the standard follow-up to this joseki. ]
;B[jd];W[mg];B[pg];W[jf]
TR[fc]
C[It is particularly effective here because White has the marked stone in place, making White 7 a severe move. <= ]
)
(;W[nq]
C[Failure.  

If White approaches with 1 at the bottom, ... ]
;B[pn]
C[... Black simply answers with 2. ]
;W[kp]
C[White completes the sequence with 3, ... ]
;B[le]
LB[md:A]
C[... letting Black defend against the threat of White A with 4. Black is satisfied with this result. <= ]
)
)