(;
AB[bb][cc][cd][dd][ee][fe][gf][hf][if][ie][id][jc][jb][ib][gb][fb]
AW[eb][fc][fd][ed][he][ge][hd][hc][hb][ha][ic]
C[Black plays.

Source:
    51st Judan Title promotional tsumego]
(;
B[db]
C[Reducing from the outside is too slow.];
W[ea];B[gc];W[ga];B[ec]
C[Black only has a ko.]
)
    (;
    B[ea]
    C[Black can take a vital point here, but ...];
    W[db]
    C[... White now extends the eye-space.];
    B[gc]
    C[Black can keep White from playing here to make 2 eyes, but ...];
    W[fa]
    LB[da:A][dc:B]
    C[... White makes miai of A and B to make the 2nd eye.];
    B[ia]
    C[With this move Black can only postpone the inevitable.];
    W[gd]
    C[White lives with territory.]
    )
    (;
    B[gc]
    LB[gd:A][ia:B]
    C[A simple, and the only, killing move.

Note that Black threatens A.];
    W[ga];B[dc]
    C[A fantastic "ugly" move that prevents White's ko resource from a previous variation.];
    W[db];B[da]
    C[The finale -- White doesn't have enough room to create a seki or force a liberty shortage.]
    (;
    W[cb];B[ec];W[gd];B[ca];W[fa];B[gb];W[ba];B[bc]
    )
        (;
        W[ec];B[ea];W[cb];B[ca]
        C[White cannot throw-in at the 1-2 point, because of the liberty shortage.]
        )
    )
)

