(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AB[qs][os][or][pq][pp][po][qo][rn][sn][nq]AW[ps][pr][qr][qq][qp][ro][so]C[Black to play and kill]
(;B[rr]C[This might work, but it ends in a ko.]
(;W[rs]
(;B[rq];W[rp])
(;B[sp]C[This might also be ko.]
(;W[rp];B[sq])
(;W[rq]C[However if White gets here it lives.])))
(;W[rq]C[White can also make seki here.];B[sq];W[rs];B[sr];W[rp]))
(;B[sq]C[This looks like a vital point but it is also ko, or seki.];W[rp];B[rr];W[rs];B[ss])
(;B[rp]C[This is teh correct move even though it looks like White can give up two stones.];W[rq]
;B[sq]C[This traps the two stones in a snap-back shape and also kills the corner.]
(;W[rr];B[sr])
(;W[rs];B[sr])))
