(;AB[bb]AB[bc]AB[bd]AB[cb]AB[eb]AB[ea]AW[ae]AW[be]AW[ce]AW[cd]AW[cc]AW[fc]AW[dc]AW[ec]AW[fb]AW[fa]AW[de]AW[ee]AW[fe]AW[fd]C[White to kill.]AP[goproblems]
(;W[ad];B[db]
(;W[ac];B[ab])
(;W[ab];B[ac];W[ba];B[aa]C[bad ko for white])
(;W[aa];B[ac])
(;W[ba];B[ac]
(;W[ca];B[aa];W[ab]C[ko])
(;W[ab];B[aa]C[bad ko for white]))
(;W[ca];B[ba]))
(;W[ac];B[ad]
(;W[ab];B[ca]TR[aa]TR[db])
(;W[aa];B[db])
(;W[ba];B[ca])
(;W[ca];B[db])
(;W[db];B[ca])
(;W[da];B[db]))
(;W[ab];B[ca]
(;W[db];B[aa]
(;W[ac];B[ad])
(;W[ad];B[ac])
(;W[ba];B[ac])
(;W[da];B[ad];W[ba]C[ko]))
(;W[ad];B[ac]TR[aa]TR[db])
(;W[ac];B[ad]TR[aa]TR[db])
(;W[ba];B[ac])
(;W[aa];B[db]))
(;W[aa];B[db])
(;W[ba];B[ca]
(;W[db];B[aa])
(;W[ad];B[ac])
(;W[ac];B[ad])
(;W[ab];B[ac])
(;W[aa];B[db]))
(;W[ca];B[db]
(;W[ba];B[ad]
(;W[ab]C[seki])
(;W[aa];B[ab]))
(;W[ad];B[ba])
(;W[ac];B[ad])
(;W[ab];B[ba])
(;W[aa];B[ad]))
(;W[da];B[db])
(;W[db];B[ad]
(;W[da];B[ab])
(;W[ca];B[ba]
(;W[ab]C[:)RIGHT])
(;W[da];B[ab]))
(;W[ba];B[ca]
(;W[aa];B[ab])
(;W[ab];B[aa]C[ko]))
(;W[aa];B[ab])
(;W[ab];B[ca]
(;W[aa]C[:)RIGHT])
(;W[ba];B[aa]C[ko])
(;W[da];B[aa];W[ba]C[ko]))
(;W[ac];B[ab]))
(;W[dd];B[db]C[:|])
(;W[ed];B[db]C[:l]))