Game of Origin4152 (13k, though this match pushed me to 12k) vs tikka (13k).
Very close game, and his mistake ended up winning it for me.
My first problem, please comment ^___^
(;AB[ae]AB[ad]AB[bd]AB[bc]AB[cc]AB[dc]AB[ec]AB[ed]AB[fc]AB[gc]AB[fb]AB[ea]AB[eb]LB[eb:2]AW[da]LB[da:1]AW[fa]AW[ga]AW[gb]AW[hc]AW[ib]AW[hd]AW[gd]AW[fd]AW[ee]AW[ef]AW[dd]AW[cd]AW[be]AW[af]AW[cf]C[Black 2 was a mistake, punish it. Assume Black will win any ko.]AP[goproblems]
(;W[fa])
(;W[bb]
(;B[cb]C[CHOICE];W[ca];B[ab];W[ba]C[Seki!RIGHT])
(;B[ab]C[]
(;W[ba];B[cb];W[ca]C[Gote seki, you can do better after bA18])
(;W[cb];B[ba]C[Sente sekiRIGHT])))
(;W[ab];B[bb]
(;W[ba];B[ac]
(;W[cb];B[aa]C[Ko, black lives.])
(;W[db];B[aa]C[Ko, black lives.]))
(;W[cb];B[ba]))
(;W[cb];B[bb];W[ba];B[ab])
(;W[ba];B[bb]
(;W[cb];B[ab])
(;W[ab];B[ac]
(;W[cb];B[aa]C[Ko, black lives.])
(;W[db];B[aa]C[Ko, black lives.])))
(;W[ca];B[bb];W[ab];B[ba])
(;W[db];B[cb])
(;W[aa];B[bb];W[ba];B[ab])
(;W[ac];B[ab];W[bb];B[cb]
(;W[ca];B[ba])
(;W[ba];B[ca])))