(;
AB[pr][or][ns][nq][np][mp][lp][ip][iq][ir][js][kr][jp][kp]
AW[rr][qq][pq][oq][mq][lq][kq][jq][mr][nr][jr]
C[White plays.]
(;
W[ms]
C[White doesn't seem to have a problem after this descent, but ...];
B[ls];W[os];B[ps]
C[... Black can use the aji of these stones to start a direct ko.  And Black takes 1st.]
)
    (;
    W[ls]
    C[The only move that works.]
    (;
    B[ks]
    (;
    W[qr]
    C[A big mistake.];
    B[os]
    C[Now Black has this classic tesuji!];
    W[qs];B[is];W[ps];B[lr];W[ms];B[or]
    C[Black captures with an under-the-stones maneuver.]
    )
        (;
        W[os]
        C[Again the only move.];
        B[ps];W[qr];B[is];W[qs]
        C[White wins the semeai.]
        )
    )
        (;
        B[os]
        C[Changing the move order doesn't help Black.];
        W[ks]
        C[Now White can dodge to here.];
        B[ms];W[is];B[hs];W[qr]
        C[Black doesn't even have a ko.]
        )
    )
)

