(;AB[cb]AB[cc]AB[bd]AW[cd]AW[dc]AW[ec]AW[fb]AW[ce]C[White to kill.]AW[cg]AW[gc]AP[goproblems]
(;W[be];B[ac]
(;W[bb];B[ba]
(;W[ab];B[db]
(;W[da];B[eb]
(;W[ea]C[The presence of the marked stone had sealed black's fate. RIGHT]TR[fb])
(;W[ca];B[ea])
(;W[ae];B[ea];W[ad];B[bc]))
(;W[eb];B[da]))
(;W[bc];B[ab])
(;W[db];B[ab])
(;W[ae];B[ab];W[ad];B[bc]))
(;W[db];B[bb])
(;W[ba];B[bb];W[ca];B[db]
(;W[eb];B[da])
(;W[da];B[ea];W[eb];B[aa]))
(;W[ae]
(;B[ba]
(;W[ad];B[db];W[bc];B[ab];W[da];B[ea];W[eb]C[RIGHT])
(;W[db];B[ad];W[ab]C[RIGHT]))
(;B[bb];W[ad];B[aa];W[ca];B[db];W[da];B[ea];W[eb]C[RIGHT])))
(;W[db];B[bb]C[Black is alive, see problem 4798.])
(;W[ac]C[Black is alive. See naviagte solution for how the exchange would take place.];B[ab];W[bb];B[ba];W[aa];B[bc];W[ca];B[db];W[eb];B[da];W[be];B[ad]C[Life in a double ko.])
(;W[ba];B[bb]C[CHOICE]
(;W[ac];B[be]
(;W[ca];B[db];W[da];B[ea]
(;W[eb];B[aa])
(;W[bf]))
(;W[bf];B[ab]
(;W[ae];B[bc];W[ca];B[db];W[da];B[ea];W[eb];B[aa])
(;W[db];B[ca]))
(;W[ab];B[bf]
(;W[bc];B[ad]
(;W[af];B[ca])
(;W[db];B[aa];W[ab];B[ca]
(;W[da];B[bc];W[af];B[ac])
(;W[ac];B[bc])
(;W[aa];B[ac])))
(;W[bg];B[af]
(;W[bc];B[ad];W[ca];B[db];W[da];B[aa]
(;W[ea];B[ab])
(;W[ab];B[ea]))
(;W[ad];B[db]))))
(;W[be];B[ac];W[ca];B[db]
(;W[eb];B[da])
(;W[da];B[ea];W[eb];B[aa]))
(;W[ab];B[ac];W[ca];B[be])
(;W[ca];B[ac];W[be];B[db]
(;W[eb];B[da])
(;W[da];B[ea];W[eb];B[aa]))
(;W[db];B[ac]
(;W[be];B[ca])
(;W[ca];B[be]
(;W[bf];B[ae])
(;W[ae];B[bf]))))
(;W[bc];B[bb];W[ac];B[ad];W[ca];B[ba]
(;W[ab];B[db];W[da];B[eb];W[ea];B[fa];W[ea];B[da])
(;W[db];B[ab]))
(;W[ad];B[ac];W[be];B[ae];W[bb];B[db];W[eb];B[ba];W[da];B[ab])
(;W[ab];B[be]
(;W[bf];B[ac];W[ae];B[bb];W[af];B[aa];W[ad];B[ca];W[bc];B[bd])
(;W[bc];B[bb]))
(;W[bb];B[ab]
(;W[ba];B[bc];W[be];B[ad])
(;W[ca];B[bc])
(;W[ac];B[ba];W[aa];B[bc];W[ca];B[db];W[eb];B[da];W[be];B[ad]C[Life in a double ko.])))