(;AW[bb]AB[cb]AB[cc]AB[cd]AB[bd]AB[ad]AB[db]AB[da]AW[ea]AW[eb]AW[dc]AW[dd]AW[ce]AW[be]AW[ae]AW[ee]AW[fc]C[White to play]AP[goproblems]
(;W[ba]
(;B[ab]
(;W[ca]C[Black is dead. After bA17 black is still dead, since black can't push at A19 or B17 and white could still atari with wB17.RIGHT])
(;W[bc];B[ac]C[Seki])
(;W[aa];B[bc];W[ac]C[Ko])
(;W[ac];B[bc]C[Seki]))
(;B[bc];W[ab]C[Black is dead])
(;B[ac];W[ab]C[Black is dead])
(;B[ca]
(;W[ac]C[Black is dead])
(;W[bc]C[Black is dead])
(;W[ab]C[Black is dead])
(;W[aa]
(;B[bc];W[ac])
(;B[ab];W[ac]C[Black is dead])))
(;B[aa];W[bc];B[ac];W[ab]C[Black is dead]))
(;W[ca];B[ba]
(;W[ac];B[aa]C[Seki])
(;W[ab];B[ac]C[Seki])
(;W[bc];B[ab]C[Black lives])
(;W[aa];B[ab]C[Black lives]))
(;W[aa];B[ba]
(;W[ca]C[];B[ab]
(;W[ba];B[bc])
(;W[bc];B[ba]C[Black lives])
(;W[ac];B[ba]C[Ko]))
(;W[ab];B[bc];W[ca]C[Ko])
(;W[bc];B[ab]C[Black lives])
(;W[ac];B[ab]C[Ko]))
(;W[ab];B[ba]LB[df:T]C[T for tenuki]
(;W[bc]C[Seki])
(;W[ac]C[Seki])
(;W[aa];B[bc];W[ca]C[Ko])
(;W[df];B[bc]C[Seki]))
(;W[bc];B[ba]
(;W[aa];B[ab]C[Black lives])
(;W[ab]C[Seki])
(;W[ac];B[ab]))
(;W[ac];B[ba]
(;W[ab]C[Seki])
(;W[bc];B[ab])
(;W[aa];B[ab]C[Ko])))