This position appeared in an actual game; white lost by half a point. But upon review, a winning move revealed itself...
(;AB[bp]AW[gk]AB[gj]AW[ps]AB[pl]AW[si]AB[sj]AW[go]AB[io]AW[lc]AB[ko]AW[lq]AB[kp]AW[ho]AB[jq]AW[ls]AB[is]AW[gr]AB[ks]AW[lr]AB[kr]AW[cj]AB[ci]AW[ek]AB[ej]AW[dk]AB[ol]AW[oq]AB[nn]AW[nk]AB[ql]AW[ok]AB[nl]AW[ml]AB[pj]AW[rh]AB[rj]AW[ri]AB[gs]AW[hr]AB[hs]AW[eq]AB[ds]AW[fq]AB[fr]AW[es]AB[fs]AW[gq]AB[hp]AW[jd]AB[ie]AW[id]AB[ee]AW[ed]AB[fe]AW[fd]AB[kf]AW[le]AB[nc]AW[md]AB[gd]AW[ld]AB[ke]AW[kd]AB[ap]AW[an]AB[be]AW[ah]AB[ae]AW[af]AB[bf]AW[ag]AB[oc]AW[od]AB[ob]AW[la]AB[na]AW[ma]AB[qk]AW[pk]AB[rb]AW[se]AB[sc]AW[sd]AB[cb]AW[ea]AB[ca]AW[da]AB[je]AW[hc]AB[hd]AW[kb]AB[mb]AW[lb]AB[dg]AW[bi]AB[bg]AW[bh]AB[ch]AW[bj]AB[iq]AW[hq]AB[ir]AW[os]AB[qs]AW[nr]AB[qr]AW[mr]AB[om]AW[pr]AW[lp]AB[mn]AW[no]AB[np]AW[mp]AB[mo]AW[ll]AB[jn]AW[fn]AB[gm]AW[hm]AB[hn]AW[im]AB[mm]AW[lm]AB[ln]AW[km]AB[kn]AW[jm]AB[in]AW[lj]AB[kk]AW[gn]AB[fi]AW[fl]AB[gi]AW[fj]AB[gl]AW[fk]AB[hl]AW[hj]AB[ik]AW[hk]AB[ip]AW[eo]AB[cr]AW[er]AB[dr]AW[bm]AB[bn]AW[cn]AB[bo]AW[co]AB[cp]AW[dq]AB[cq]AW[cl]AB[db]AW[eb]AB[dc]AW[ec]AB[hf]AW[mk]AB[jk]AW[kj]AB[hi]AW[ij]AB[jg]AW[ih]AB[ii]AW[ji]AB[jh]AW[ki]AB[lf]AW[li]AB[kh]AW[lh]AW[nj]AW[mh]AW[oi]AB[lg]AW[mg]AB[mf]AW[ng]AB[me]AW[ne]AB[nd]AW[pe]AB[nf]AW[oe]AW[og]AB[qi]AW[pi]AB[of]AW[pf]AW[qg]AW[qh]AB[qd]AW[qe]AB[rd]AW[re]AB[mc]AW[gc]AB[jj]AW[jc]AB[dj]AW[gp]AB[qj]AW[lo]AB[pm]AW[op]AB[po]AW[on]AB[qp]AW[pq]AB[qq]AW[oo]AB[pn]AW[kq]AB[nq]AW[dp]AB[dd]AW[pp]AB[pd]C[White has eight prisoners, and komi is 0.5. White needs just one more point to win! Can you help her find it?FORCE]AP[goproblems]
(;W[br]
(;B[bs]
(;W[ar]C[];B[bq];W[am]
(;B[aq]C[];W[ao];B[as]C[By threatening a seki, white forces black to fill in an extra point of territory. White: 80.5, Black 80. White wins!CHOICERIGHT])
(;B[oj]C[Black thinks he can ignore this. Now what?];W[ao]C[Seki! White: 80.5, Black 75. A solid win for White.CHOICERIGHT]))
(;W[aq];B[bq];W[am];B[ar]C[White: 80.5, Black: 81. White loses.CHOICE])
(;W[am];B[ar]C[Now what?];W[ao]C[White can't force another move by black without playing inside black's territory. White: 80.5, Black: 81. White loses.CHOICE]))
(;B[ar]
(;W[bs]C[];B[bq];W[am]
(;B[cs]C[];W[ao];B[as]C[By threatening a seki, white forces black to fill in an extra point of territory. White: 80.5, Black 80. White wins!CHOICERIGHT])
(;B[oj]C[Black thinks he can ignore this. Now what?];W[ao]C[Seki! White: 80.5, Black 75. A solid win for White.CHOICERIGHT]))
(;W[am];B[bs]C[Now what?];W[ao]C[White can't force another move by black without playing inside black's territory. White: 80.5, Black: 81. White loses.CHOICE])))
(;W[am];B[bs]C[White: 80.5, Black: 81. White loses.])
(;W[bs];B[br];W[ar];B[aq]C[White: 80.5, Black: 82. White lost a point!])
(;W[ar];B[br];W[bs];B[aq]C[White: 80.5, Black: 82. White lost a point!])
(;W[ei];B[di];W[eh];B[hh]C[])
(;W[ge];B[he];W[gf];B[gg]C[])
(;W[ao];B[am]C[])
(;W[bq];B[br]C[])
(;W[aq];B[ar];W[br];B[bq];W[bs];B[cs];W[am];B[as]C[White: 80.5, Black: 81. White loses.])
(;W[cs];B[bs])
(;W[as];B[ar]C[])
(;W[qo];B[ro]C[])
(;W[pc];B[pb]C[]))