(;
AB[rm][nn][lo][lp][mo][po][qo][ro][qp][mq][pq][pr][lr]
AW[mp][np][op][pp][rp][rq][oq][qq][nr]
C[Black plays.]
(;
B[sp]
C[The obvious hane is too slow.];
W[sr];B[qr];W[rr]
C[White wins the semeai to make eyes.]
)
    (;
    B[rr]
    C[Sometimes Black can sacrifice the 2 inside stones to squeeze a connection to the outside, but ...];
    W[qr];B[sq];W[sp]
    C[... White has an extra liberty.];
    B[qs];W[sr]
    C[Black doesn't even have a ko.]
    )
    (;
    B[qr]
    C[Creating more inside liberties doesn't work either.];
    W[rr];B[or];W[os]
    )
    (;
    B[sr]
    C[This placement tesuji is best!]
    (;
    W[qr]
    C[Descending here is a mistake.];
    B[sp]
    (;
    W[sq];B[qs];W[so];B[rr]
    C[White collapses.]
    )
        (;
        W[ps]
        C[No better.];
        B[sq]
        C[White has only one eye.];
        W[mr];B[ms];W[ns];B[or]
        )
    )
        (;
        W[rr]
        C[So White has no choice but to block here.];
        B[rs]
        C[Now Black has time to set up the squeeze to connect out.];
        W[qs];B[sp]
        C[Ko is the best for both sides.]
        )
    )
)

