(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play and kill]AW[po][mp][pp][mq][pq][mr][or][qr][rs]AB[on][pn][lo][mo][no][qo][qp][kq][qq][lr][rr][sr]
(;B[np]C[If plack tries to take away the eye space towards the middle,
white can easily live.]
;W[nq]
;B[op]
(;W[qs]C[White can try this way.]
(;B[oq]
;W[ns])
(;B[ns]C[But thisblack kills.]
;W[ms]
;B[os]))
(;W[ns]C[So white had better make this eye.]
;B[ps]
;W[qs]
;B[oq]
;W[pr]))
(;B[ns]
;W[ms]
;B[ps]
;W[qs]
;B[os]
;W[np]C[This is easy life.])
(;B[op]
(;W[nq]
;B[ns]
;W[ms]
;B[ps]
;W[qs]
;B[os]C[This dies])
(;W[oq]
;B[ns]
;W[ms]
;B[ps]
;W[qs]
;B[os]
;W[np]
;B[oo]
;W[nr]C[So white must play this way.]))
(;B[ps]C[This is the first move here, but the rest is quite hard to read.]
;W[np]
;B[qs]
;W[oo]
;B[oq]C[This is just where white wants to go.]
(;W[ms]C[This is white's strongest defence.]
;B[pr]
;W[op]
;B[os]
;W[ns]
;B[nr]
;W[nq]
;B[or]C[Balck connects to sacrifice seven stones.]
;W[qr]
;B[or]C[Black plays back in on the vital point and white is dead!])
(;W[nq]
;B[ns]
;W[ms]
(;B[os]C[This would fail for black as his corner stones have a weakness.])
(;B[pr]C[But this is atari.]))
(;W[pr]
(;B[ns]
;W[ms]C[This is a black error.])
(;B[nq]C[Black may play here.]
;W[os]
;B[qs]
;W[ms]
;B[nr]C[This is seki])
(;B[ms]C[This is the move that keeps white dead]
;W[ns]
;B[nq]))))
