(;
AB[lb][lc][ld][pb][mc][od][pd][qd][me][ne][oe]
AW[mb][ob][qb][qc][nc][nd][md][rd][le][lf][qe][qf][ng][pg]
C[Black plays.

Source:
    From the yose volume of Gokyo Seimyo, a nearly 200 year old problem set.]
(;
B[nb];W[na];B[oc];W[nb];B[pa];W[pc]
C[Up to here, Black has this easy to read forcing sequence, but now seems to have reached a dead end.  Where is White's weakness?];
B[rb]
C[A nice tesuji that many players might overlook.]
(;
W[qa]
C[White captures 2 stones, but ...];
B[rc];W[oa];B[re]
C[... Black captures a stone to create enough liberties to win the semeai.]
)
    (;
    W[rc]
    C[Protecting the cut/atari here is necessary, but doesn't end White's problem.];
    B[qa];W[la]
    C[And Black will take this huge ko first.]
    )
)
    (;
    B[pc]
    C[Too slow.];
    W[pa]
    C[And the reader can verify that White has enough liberties to connect.]
    )
)

