(;AB[bc]AB[cc]AB[cb]AB[cd]AB[dc]AB[ec]AW[bd]AW[be]AW[ce]AW[de]AW[dd]AW[ed]AB[bf]AB[cf]AB[df]AW[ef]AW[fg]AW[ff]AW[fh]AB[eg]AB[eh]AB[ei]AW[fc]AW[eb]AB[fd]AW[gc]AB[fb]C[White to play. Many thanks to kaf, Clydevil, BartTM and Bass for their corrections.CHOICE]AW[hb]AB[ch]AP[goproblems]
(;W[da]
(;B[ba]
(;W[ab];B[ac]
(;W[ad];B[db]
(;W[fa]C[Correct. Note that blocking at A16 gives Black one more local threat - blocking at A15 would be better, and would also give better prospects for endgame (thanks to BartTM for this comment).RIGHT])
(;W[ea];B[fa]))
(;W[gb];B[ae])
(;W[ae];B[db]
(;W[fa]C[RIGHT])
(;W[ea];B[fa]))
(;W[ee]C[];B[db]
(;W[fa]C[RIGHT])
(;W[ea];B[fa]))
(;W[af];B[db]
(;W[fa]C[RIGHT])
(;W[ea];B[fa]))
(;W[fa];B[ae]))
(;W[fa];B[ab])
(;W[ac];B[ab])
(;W[gb];B[ab]))
(;B[db]C[RIGHT]
(;W[fa]C[RIGHT])
(;W[ea];B[fa])
(;W[ac];B[ea])
(;W[ca];B[ba]))
(;B[ac]
(;W[ad];B[db]
(;W[fa]C[Correct. Note that blocking at A16 gives Black one more local threat - blocking at A15 would be better, and would also give better prospects for endgame (thanks to BartTM for this comment).RIGHT])
(;W[ea];B[fa])
(;W[ba];B[ea])
(;W[ca];B[ba]))
(;W[ae];B[db]
(;W[fa]C[RIGHT])
(;W[ea];B[fa])
(;W[ba];B[ea])
(;W[ca];B[ba]))
(;W[af];B[db]
(;W[fa]C[RIGHT])
(;W[ea];B[fa])
(;W[ba];B[ea]))
(;W[ee];B[db]
(;W[fa]C[RIGHT])
(;W[ea];B[fa])
(;W[ba];B[ea])
(;W[ca];B[ba]))
(;W[ca];B[ae])
(;W[ba];B[ae])
(;W[fa];B[ae])
(;W[gb];B[ae])
(;W[ab];B[ae])))
(;W[ac];B[ab]
(;W[ad];B[ba])
(;W[ba];B[ae]))
(;W[ab];B[ac]
(;W[ad];B[ea])
(;W[gb];B[ae])
(;W[ae];B[ea])
(;W[ee];B[ea])
(;W[af];B[ea])
(;W[ba];B[ea])
(;W[ca];B[ea]))
(;W[gb];B[ba]
(;W[ab];B[ac]
(;W[ad];B[da])
(;W[fa];B[ae])
(;W[da];B[ae])
(;W[ae];B[da])
(;W[af];B[da])
(;W[ee];B[da]))
(;W[da];B[ab])
(;W[ac];B[ab]))
(;W[bb];B[ab];W[ba];B[ea])
(;W[ba];B[ac]
(;W[ad];B[ea])
(;W[gb];B[ae])
(;W[ae];B[ea])
(;W[af];B[ea])
(;W[ee];B[ea])
(;W[fa];B[ae])
(;W[da];B[ae])
(;W[ca];B[da]))
(;W[fa];B[ba]
(;W[ab];B[ac]
(;W[ad];B[da])
(;W[da];B[ae])
(;W[gb];B[ae])
(;W[ae];B[da])
(;W[af];B[da])
(;W[ee];B[da]))
(;W[da];B[ab])
(;W[gb];B[ab])
(;W[ad];B[ab])
(;W[ae];B[ab])
(;W[ac];B[ab]))
(;W[ca];B[ba]
(;W[ab];B[ac]
(;W[ad];B[da])
(;W[ae];B[da])
(;W[af];B[da])
(;W[ee];B[da]))
(;W[da];B[ab])
(;W[ac];B[ab])
(;W[db];B[da]))
(;W[ea];B[ba]
(;W[ab];B[ac]
(;W[ad];B[da])
(;W[gb];B[ae])
(;W[ae];B[da])
(;W[af];B[da])
(;W[ee];B[da])
(;W[fa];B[ae]))
(;W[ac];B[ab]))
(;W[gd];B[ea])
(;W[fe];B[ea])
(;W[ee];B[ea])
(;W[af];B[ea])
(;W[ad];B[ea]))