(;
AB[qo][qp][pp][mq][oq][or][rq][sq]
AW[qm][pn][np][op][rp][pq][qq][rr]
PL[W]
C[White plays.

Source:
    "Tesuji", James Davies]
(;
W[sp]
C[Capturing the 2 stones seems natural, but ...];
B[qr]
C[... Black squeezes.];
W[sr];B[rq];W[sq];B[pr];W[rq]
C[If White persists on capturing the marked stones, Black can force White into this famous "tombstone" shape.]
TR[qo][qp][pp];
B[ro]
C[White collapses.]
)
    (;
    W[qr]
    C[At first glance, connecting seems too slow.];
    B[ro]
    C[Black captures a stone to make at least one eye, but ...];
    W[sr];B[sp];W[sn]
    C[The tesuji.]
    (;
    B[rn];W[rm];B[pr];W[sm];B[qs];W[so]
    C[White wins the semeai.]
    )
        (;
        B[pr]
        C[No better.];
        W[so];B[rp];W[rn]
        C[Again, White wins the semeai by one move.]
        )
    )
)

