(;
AB[oo][op][kq][mq][nq][pq][pr][qq][lr]
AW[qm][pp][qp][rp][oq][or][rq][mr][nr]
C[Black plays.]
(;
B[qs]
C[A stylish-looking move, but unsatisfactory here.];
W[rr]
C[For example ...];
B[os];W[qr];B[ms];W[ps];B[pr];W[pq];B[ns];W[rs]
C[Black can do better.]
)
    (;
    B[ps]
    C[Correct.]
    (;
    W[qs];B[rr]
    C[And White cannot capture the original corner stones.];
    W[os]
    C[For example ...];
    B[qr];W[sr];B[rs]
    )
        (;
        W[qr];B[rr];W[rs]
        (;
        B[ms]
        C[Black rescues the original corner stones.  White doesn't even have a ko.]
        )
            (;
            B[qs]
            C[Big mistake.];
            W[sr]
            C[Now Black has to fight a ko for the corner stones.]
            )
            (;
            B[sr]
            C[Even worse.];
            W[os]
            C[Black loses all the corner stones.]
            )
        )
    )
)

