(;
AB[dq][dp][cm][cb][cc][dd][ed][fc][fe][dg][pd][mc][ql][pp][lq]
AW[bb][bc][cd][ce][de][ee][ef][hd][qf][pj][jq][gq]
C[White plays.

Source:
    "Correcting the Mistake", Kato Honinbo
    Go World #12, pp. 57-58];
LB[dj:A][qq:B][qc:C][me:D]
C[Hint:  White's correct move is either at A, B, C, or D.]
(;
W[qq]
TR[lq][ql]
C[Given Black's marked double-wing formation, White's invasion in the lower right corner is an absolute must.  White shouldn't miss this move for anything.

If Black were to play here instead, Black's shape with the 4 stones would be too good.];
B[qp];W[pq];B[oq];W[or];B[nq];W[rp];B[ro];W[rq];B[qn]
TR[ql][lq]
LB[ck:A]
C[White steals the corner territory in sente, and Black's marked stones are too close to Black's other stones.

Now White can play a large point elsewhere, e.g., at A, or one of the other hint points shown at the beginning of the problem.]
)
    (;
    W[qc]
    C[White wants to invade here so as to force Black into strengthening White's right side stones.  But ...];
    B[qd];W[pc];B[od];W[oc];B[nc];W[rd];B[re];W[rc];B[qe];W[of];B[nf];W[ng];B[mf]
    C[... after this joseki White has to make another move to defend.];
    W[og]
    C[Now White's upper right groups are strong, but ...];
    B[qq]
    C[... with a nice framework at the top Black can now switch to the huge point in the lower right.]
    )
    (;
    W[dj]
    C[White's pincer here would be good, if Black responds.]
    (;
    B[ei]
    C[For example, if Black jumps out, ...];
    W[dl]
    C[... this White extension works beautifully.  But Black will not cooperate this way.]
    )
        (;
        B[qq]
        C[But Black will leave the upper left stone as light, and take the all-important lower right point.]
        )
    )
    (;
    W[me]
    TR[hd]
    C[Given that White plays at the top, this move is good.  White reduces Black's top formation, and reinforces the marked stone and the right side stones.

But ...];
    B[qq]
    C[... again Black takes the lower right point.]
    )
)

