(;
AB[cp][cq][dq][iq][jq][kq][lq][er][hr][kr][ks][mr][ls]
AW[mo][dp][ep][ip][jp][lp][fq][gq][hq][mq][nq][ir][jr][nr][ns]
C[Black plays.]
(;
B[is]
C[Capturing the 2 stones immediately fails.];
W[gs]
LB[gr:A]
C[Alan Huang pointed out that this move kills Black.  The original solution with White A only leads to a ko.];
B[js];W[ms]
)
    (;
    B[gs]
    C[Also doesn't work.];
    W[gr];B[is]
    C[White has a picnic ko for the lower middle group.]
    )
    (;
    B[gr]
    C[At 1st glance, this push looks like a vulgar move.];
    W[fr]
    C[After White wedges here, Black seems to have a liberty shortage.]
    (;
    B[is]
    C[And if Black captures now, ...];
    W[gs];B[hs];W[js];B[hr];W[ms]
    C[... Black has only one eye.]
    )
        (;
        B[hs]
        C[But Black has this famous tesuji resource to save the stones.]
        (;
        W[fs]
        C[White can split the Black into 2 groups, but ...];
        B[ms];W[gs];B[is];W[js];B[hr]
        C[... Black can make 2 eyes.]
        )
            (;
            W[ms]
            C[No better.];
            B[fs]
            C[Black has just enough liberties on the right to connect.]
            )
        )
    )
)

