(;
AB[dc][qc][cd][od][dh][pm][pn][qm][op][pp][qq][rq]
AW[hc][kc][qd][ce][qn][rn][dp][qp][rp][pq][pr][qr]
TR[kc]
C[Black's response to White's marked extension?

Source:
The Great Joseki Debate
Go World #27, p. 45,  Spring 1982];
LB[qe:A][rd:B][pd:C]
C[A, B, or C?]
(;
B[qe]
C[This attachment gives Black both profit and sente.];
W[pd]
C[A likely joseki follows.];
B[pc];W[pe];B[rd];W[re];B[qf]
(;
W[oe];B[rc];W[nd];B[oc];W[pg];B[rf]
C[A solid move that threatens to cut severely at A.]
LB[ne:A];
W[ng]
C[So White protects to bring the joseki to an end.];
B[cn]
C[Now Black effectively use sente to play on the left side.]
(;
W[fp];B[de]
C[Black not ony has top right profit, but also has a good left side formation.

White has made good top right thickness, but has no way to make good use of that.]
)
    (;
    W[de]
    C[White can try to make use of the top left stone, but ...];
    B[ed]
    C[... because of this kosumi, Black can expect to do well in any fighting.]
    )
)
    (;
    W[rc]
    C[Cutting here looks tempting, but is a mistake.];
    B[of]
    C[Black can squeeze from the outside.];
    W[sd];B[pf];W[rf];B[rg];W[rb];B[oe]
    C[This result is probably the best that White can do, but Black is satisfied with the outside thickness.]
    )
)
    (;
    B[rd]
    C[If Black hanes here, ...];
    W[qe]
    C[... White will probably choose to extend with the following sequence.];
    B[re];W[pc];B[pd];W[qf];B[qb]
    C[But after Black extends, which stresses attacking White's top right stones, White can still tenuki to play on the left side.];
    W[de]
    C[For example ...];
    B[fc];W[cj]
    C[The game will hinge on how effectively Black can attack White's weak stones.  But in any event, Black has a difficult game.]
    )
    (;
    B[pd]
    C[Another common joseki.];
    W[qe]
    (;
    B[pb];W[qh]
    C[The joseki ends, so Black has sente to play on the left side.  But ...];
    B[cn];W[fp];B[de]
    C[... although the left side is the same as the main line, Black's top right profit is much less.  Also, Black has no groups to attack.]
    )
        (;
        B[rc]
        C[In this case, descending is bad, because ...];
        W[ph]
        C[... White will stake out a high position here or at A.  And White can aim at the vital point at B.]
        LB[pi:A][ob:B]
        )
    )
)

