(;
AB[rd][qd][qe][pf][pg][ph][pi][pj][pk][ol][om][on][po][pp][pq]
C[Black plays.]
AW[re][rf][qf][rh][qj][qk][pl][pm][pn][qo][qp][qq];
B[ri];W[qi];B[rg];W[qg];B[qh];W[sg];B[sj]
C[Tesuji!  Black creates a subtle double threat.]
(;
W[rl]
LB[ql:A]
C[White can protect the cut at A, but ...];
B[sh]
C[... Black can start a picnic ko for White's stones above.]
)
    (;
    W[sh]
    C[But what does Black do, if White simply defends against the ko?];
    B[ql]
    TR[pl][pm][pn]
    C[Black's cut here threatens to capture the 3 marked stones.];
    W[rl]
    C[White can defend again, but ...];
    B[rk]
    C[... after Black cuts here, White has a not so obvious liberty shortage.];
    W[qm];B[se]
    (;
    W[sf]
    C[Stubbornly defending here is a mistake.];
    B[sd]
    LB[si:A]
    C[White is powerless to prevent the atari at A.]
    )
        (;
        W[si]
        C[The toughest defense, but ...];
        B[sd];W[rj];B[sf]
        C[... Black still captures 4 stones in gote.]
        )
    )
)

