(;
AB[pd][pj][pp][nc]
AW[nd][cd][dq]
TR[nc]
PL[W]
C[White's response to the marked play?

Source:
    American Go Journal, vol. 33, p. 21
    "What's Wrong With That Move?", Nakayama Noriyuki];
W[mc]
C[Black's previous attachment is improper, and White's block here is good.];
B[oc]
C[An ordinary looking sequence follows.];
W[md];B[pf];W[ic]
C[White is grateful for this result.  White's top shape is stronger.  And Black's top right corner has terrible aji.

The following sequences cover some of the follow-up ideas.]
(;
B[ec]
C[For example, if Black invades the top left here, ...];
W[dc];B[ed];W[df]
C[... White can squeeze the 2 heavy stones from the left and right.]
)
    (;
    W[qc]
    C[Black is wrong to think that the top right is secure territory.  Sooner or later, White can expose the weakness with this invasion.]
    (;
    B[qd];W[rd];B[re];W[rb]
    (;
    B[pb]
    C[Blocking here is too greedy.];
    W[qb]
    LB[pc:A]
    C[White threatens A.]
    )
        (;
        B[sd]
        C[Of course, Black can force here, but ...];
        W[sc]
        C[... White has a ko.  Black takes the ko 1st, but even without any ko threats, White will still be happy to make 2 moves elsewhere on the board.]
        )
    )
        (;
        B[rd]
        C[Black might also try this tricky defense, but ...];
        W[mb]
        C[... White can avoid complications and still obtain a good result by descending here.];
        B[nb]
        C[Insisting on keeping the corner territory is a mistake.];
        W[qe]
        C[White can choose when to make this placement.];
        B[qd];W[od];B[pc];W[pe]
        C[After ripping through the ride side, Black cannot be in a good mood.]
        )
    )
)

