This is a nice little problem i wanted to share with you :-)
(;AW[qr]AW[pq]AW[oq]AW[or]AW[os]AW[ps]AW[rq]AW[rp]AW[sr]AW[so]AW[rn]AW[rm]AW[sl]AW[rk]AW[ql]AW[pk]AW[pj]AW[qj]AW[rj]AB[ns]AB[nr]AB[nq]AB[op]AB[pp]AB[qq]AB[qp]AB[qo]AB[ro]AB[qn]AB[qm]AB[pl]AB[ok]AB[oj]AB[pi]AB[qi]AB[ri]AB[si]AB[sj]AB[sk]AB[ol]AB[rr]C[White's territory seems to be quite secure. But black has an evil plan in mind to shock white :)]AP[goproblems]
(;B[sn]C[good];W[sm];B[rs]C[Yes.. that's it. White cannot approach from either side so it's seki :)RIGHT])
(;B[sp];W[sq];B[sn];W[sm];B[rs]C[This is seki, but it is 1 point worse than the correct solution. Thw throw-in at T4 wasn't necessary...])
(;B[rs];W[sn]C[White lives whith 12 points. Black didn't gain anything and only helped white...]))