(;
AB[mb][mc][rb][rc][od][pd][qd]
AW[qc][rd][re][qe][qh]
C[White plays.

Source:
    From the endgame volume of Gokyo Seimyo, a nearly 200 year old problem set.]
(;
W[sc]
C[Too slow.];
B[sb]
C[Black seals off the corner.];
W[qb];B[pb];W[ra];B[sd]
)
    (;
    W[qb]
    C[Bad timing.];
    B[sb]
    C[Black can take the vital point.]
    (;
    W[ob]
    C[For example ...];
    B[pb];W[pc];B[oc];W[pa];B[ra];W[qa];B[na];W[oa];B[nb]
    )
        (;
        W[pb];B[ob]
        )
    )
    (;
    W[sb]
    C[The must-know endgame tesuji.]
    (;
    B[sc]
    C[If Black tries to greedily take the entire corner, ...];
    W[qb]
    C[... Black has a liberty shortage problem.];
    B[pb];W[ra]
    C[Black has to fight a heavy ko for the entire corner.]
    )
        (;
        B[qb]
        C[Black can play safe, but then ...];
        W[sc]
        C[... White reduces the corner.]
        )
    )
)

