(;
AB[qm][pn][qo][ro][op][oq][or][os][qr][qs]
AW[qp][rp][pq][pr][ps][rr]
C[Black plays.]
(;
B[pp]
C[Obvious, simple, and wrong.];
W[qq];B[sp]
C[This atari looks good, but ...];
W[rs];B[sr]
C[... Black has to jump here to prevent 2 eyes.];
W[sq];B[rq]
C[Originally, the solution stated that Black only has a ko.  However, Huasong Yin 7d pointed out that White actually lives!];
W[ss]
C[White has an extra liberty to capture 2 stones to live outright.]
)
    (;
    B[sp]
    C[This correct move order is important.]
    (;
    W[sq];B[pp]
    C[Now White dies from a liberty shortage.]
    )
        (;
        W[rq];B[pp];W[qq];B[sq]
        C[White dies.]
        )
        (;
        W[qq]
        C[No better.];
        B[sq]
        )
    )
)

