(;
AB[pb][pc][qd][rd][re][qf][qg][rg]
AW[qc][rc][ob][oc][pd][pe][qe][pf][rf][ne]
C[Black plays.

Source:
    Endgame volume of Gokyo Seimyo, a nearly 200 year old problem set.]
(;
B[sc]
C[The obvious move here clearly doesn't work well.];
W[sb]
C[White only needs to block.  Black's liberty shortage prevents a reduction of White's corner.];
B[rb];W[sd];B[sf];W[qb]
)
    (;
    B[rb]
    C[This clamp on the 2-2 point is often the tesuji, but ...];
    W[sd]
    C[... White can close off the corner in sente.];
    B[sf];W[qb]
    C[Black has nothing.]
    )
    (;
    B[sb]
    C[A surprising 2-1 point endgame tesuji.];
    W[sd]
    C[White still has this sente hane, but ...];
    B[sf]
    C[... now White has a problem.]
    (;
    W[sc]
    C[Too greedy.];
    B[qb];W[rb];B[ra]
    C[Black has a ko for the entire corner.]
    )
        (;
        W[rb]
        C[So White has no choice but to pull back here.];
        B[ra];W[pa];B[se]
        TR[sd]
        C[Black can capture the marked stone to reduce White's corner.]
        )
    )
)

