(;
AB[fb][hb][fc][cd][ed][fd][ce][bf][df][ef]
AW[fa][bb][eb][dc][ec][dd][de]
C[Black plays.

Source:
    Xuan Xuan QiJing, a 14th century problem set.]
(;
B[bc]
C[Obvious ... and a mistake.];
W[cc];B[ab];W[bd];B[ad]
C[Black only has a ko.]
)
    (;
    B[bd]
    C[A stylish move, but also fails here.];
    W[ca]
    C[White has this fall-back move to make eye-shape.];
    B[ab];W[ac];B[bc];W[aa];B[ad];W[cc]
    C[Black only has a ko.]
    )
    (;
    B[ad]
    C[A fantastic move, and the only move that works!]
    (;
    W[ac];B[bc];W[ab];B[da]
    (;
    W[cc];B[ba];W[bd];B[ae];W[ea];B[cb]
    C[Black forms a dead shape.]
    )
        (;
        W[ea];B[cb];W[cc];B[ba]
        C[Black forms a dead shape.]
        )
    )
        (;
        W[ab]
        C[Also fails.];
        B[da]
        (;
        W[ea];B[cb];W[cc];B[ba]
        )
            (;
            W[db];B[cc];W[cb];B[ea]
            )
        )
    )
)

