(;AB[da]AB[db]AB[dc]AB[cc]AB[bc]AB[bd]AB[be]AB[ae]AW[af]AW[bf]AW[ce]AW[cd]AW[dd]AW[ec]AW[eb]AW[ea]AW[ed]AW[cf]AW[bb]C[Black to get the best result possible.]AP[goproblems]
(;B[ac];W[ab]C[A18 is just a small ko threat which White won't play before the endgame; if Black tenukis all White could get is a seki + 1 point in double gote. Prevent even that.]
(;B[ba]C[Black lives with 8 points. So easy, yet so easily overlooked.RIGHT])
(;B[cb];W[ba]C[Seki.])
(;B[ca];W[ba]C[Seki.])
(;B[aa]C[Seki as it stands, and White has one point.]))
(;B[ab];W[ac]
(;B[ad]
(;W[ca]
(;B[aa]C[Seki])
(;B[ba];W[aa]C[Ko])
(;B[cb];W[ac])
(;B[ac];W[ba]))
(;W[ba]
(;B[ca]C[Seki])
(;B[cb]C[Seki])
(;B[aa];W[ac]
(;B[aa];W[ab])
(;B[cb];W[ca])
(;B[ca];W[cb])
(;B[ab];W[aa]
(;B[ca];W[ac]C[Ko])
(;B[cb];W[ac]C[Ko])))))
(;B[ba];W[aa]
(;B[ca];W[ab]C[Sente seki. Not bad, but not good enough.])
(;B[cb];W[ca]C[Ko!])
(;B[ab]C[Ko])
(;B[ad];W[ca];B[ab]C[Ko]))
(;B[cb];W[aa]
(;B[ba];W[ca]C[Ko])
(;B[ad];W[ca]))
(;B[aa];W[ba]
(;B[ab];W[aa]C[Sente seki. Not bad, but not optimal either.])
(;B[aa];W[ab])
(;B[cb];W[ab])
(;B[ca];W[ab])
(;B[ad];W[ab]))
(;B[ca];W[aa]
(;B[ba];W[ab]C[Sente seki. Not bad, but you can do better.])
(;B[ad];W[ab])))
(;B[ba];W[ac]
(;B[cb];W[ab]C[Sente seki; nice, but Black could live with points.])
(;B[ab];W[aa]
(;B[ca];W[ab]C[Sente seki; just not optimal.])
(;B[cb];W[ca]C[Ko])
(;B[ab]C[Ko])
(;B[ad];W[ca];B[ab]C[Ko]))
(;B[aa];W[ab]
(;B[ca]C[Seki])
(;B[cb];W[ca]
(;B[ba]C[Seki])
(;B[aa];W[ad]))
(;B[ad];W[ca]))
(;B[ca];W[ab]C[Sente seki. Nice but just not good enough.])
(;B[ad];W[ab]C[Black is dead!]))
(;B[cb];W[ac]
(;B[ab];W[aa]
(;B[ba];W[ca]C[Ko])
(;B[ad];W[ca]))
(;B[ba];W[ab]C[Sente seki, which is not bad but not the best either.])
(;B[ad];W[ca])
(;B[aa];W[ba]C[Dead.]))
(;B[ca];W[ac]
(;B[ab];W[aa]
(;B[ba];W[ab]C[Sente seki, Black can do better.])
(;B[ad];W[ab]))
(;B[ba];W[ab]C[Sente seki, just not the best.])
(;B[aa];W[ba]C[Lethal.])
(;B[ad];W[ab]C[RIP]))
(;B[ad];W[ab]
(;B[ba];W[ac]C[Dead.])
(;B[cb];W[ba])
(;B[ca];W[ba]))
(;B[aa];W[ac]
(;B[ba];W[ab];B[ca]C[Seki])
(;B[ab];W[ba];B[ab]C[Seki];W[aa]C[Sente seki. Not bad, but not optimal either.])
(;B[ca];W[ba])
(;B[cb];W[ba])
(;B[ad];W[ab])))