(;GM[1]FF[4]AP[Drago:4.22.03]SZ[19]CA[UTF-8]AB[qr][qq][qp][qo][po][oo][nn][ln][mn][lo][lp][kq][kr][ls][np]AW[no][mq][mp][mo][lq][nr][op][pp][pq][pr]C[Black to play and kill.]
(;B[nq]C[This looks like a key move but
is incorrect timing.]
(;W[os];B[ms]
;W[oq]C[White lives.])
(;W[ms];B[os]
(;W[oq]
(;B[ns];W[lr]
;B[mr]C[White gets a ko.])
(;B[ps];W[lr];B[ns]
;W[ks]C[White lives.]))
(;W[ps];B[mr];W[oq]
;B[ns]C[White is dead.]))
(;W[oq]
;B[os]C[Black can connect either way.]))
(;B[os]C[Correct.]
(;W[or]
;B[nq]C[Now this is correct.];W[ps]
(;B[ns];W[ms];B[mr]
(;W[oq]
;B[ns]C[White is dead.])
(;W[lr]C[This is a snap-back.];B[mr]))
(;B[mr]C[This is incorrect.];W[oq];B[ns]
;W[lr]C[White can trap the edge stones to live.]))
(;W[nq]C[White can try this also.];B[or]
(;W[ps];B[ns];W[ms];B[mr];W[lr]
;B[ms]C[The edge stones escape.])
(;W[ms];B[ps];W[lr]
;B[oq]C[White is dead.]))))
