(;AB[ab]AB[bc]AB[cc]AB[bd]AB[be]AW[cd]AW[ce]AW[cf]AW[bf]AW[ec]AW[dc]AW[cb]AB[eb]AW[da]C[make two eyes]AP[goproblems]
(;B[bb];W[ba];B[db];W[fb];B[ca]C[no need for ko])
(;B[db];W[ba];B[fb];W[bb];B[ea];W[ae];B[ca])
(;B[ba]
(;W[db];B[bb]C[RIGHT])
(;W[bb];B[db];W[fb];B[ca]C[RIGHT])
(;W[ae]C[CHOICE]
(;B[bb]
(;W[ad];B[db];W[fb];B[ca]C[RIGHT])
(;W[db]C[CHOICE];B[ad]C[RIGHT]))
(;B[ad];W[bb];B[af];W[db]C[now black has tu run with no eyes])
(;B[db];W[fb]
(;B[ad]C[RIGHT])
(;B[ca]C[RIGHT])
(;B[bb]C[RIGHT]))))
(;B[ae];W[ba]))