(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AB[qr][qq][pq][qs][mq][mr][mp][mo][no][oo][po][qn][rn]AW[rr][rq][rp][qp][pp][op][np][or][qo]C[Black to play and kill]
(;B[oq]C[White has possibly one eye in the corner so Black must rescue the stones.];W[nq];B[nr]
;W[ps]C[This fails as Black is short of liberties.])
(;B[os];W[ns];B[nr];W[ps];B[oq]
;W[nq]C[Again Black is short of liberties.])
(;B[ns]C[This kosumi is the correct move.]
(;W[nr]C[If White here, Black just connects];B[os])
(;W[os];B[oq];W[nq];B[nr]
;W[rs]C[The edge stones are in
seki, but the main white group only has one eye, so it is only a
temporary seki.])
(;W[ps];B[os];W[pr]
;B[oq]C[Again Black escapes.])
(;W[pr];B[os];W[ps]
;B[oq]C[Again Black okay.])))
