(;GM[1]FF[4]SZ[19]AP[SmartGo:0.4.1.2]CA[UTF-8]
GN[167ex-v2]
PB[Black to play and live]
RU[Japanese]ST[2]
AB[rp:rs][oq:or][nr]
AW[qn][ro][op:qp][sp:sq][mq:ms][nq]
(;B[sr]
C[If Black tries to make the corner eye, then White can kill the big eye.]
(;W[ps]
C[This is the move that does it.]
(;B[pr]
C[If Black plays here White can easily make the eye false.];W[ns];B[os];W[qr]
;B[qs];W[qq];B[so];W[sp])
(;B[pq]
(;W[qq];B[qr];W[ns];B[so];W[sp])
(;W[ns]
(;B[os];W[qq])
(;B[so];W[sp];B[os];W[qq])))
(;B[os]
C[Other moves quickly fail for Black.];W[pr];B[pq];W[qq])
(;B[qq]
(;W[pq];B[pr];W[ns])
(;W[ns]
(;B[os];W[pq])
(;B[pr];W[os];B[qs];W[pq]))))
(;W[pr]
C[White should not play here as the first move.];B[pq];W[qq];B[qr];W[ps]
;B[so];W[sp];B[qs]
C[Black makes two eyes]))
(;B[pq]
C[If Black tries to seal -off the big eye first...];W[qq];B[qr];W[ps]
C[White ensures the big eye is the only eye.]
(;B[os];W[sr]
C[Then takes the corner eye.])
(;B[sr]
(;W[pr]
C[The same shape as before.];B[so];W[os];B[sp])
(;W[ns]
C[So again White plays here])))
(;B[ps]
C[So White's killing move must be Black's best move.
There is nothing White can do to stop two black eyes.]
(;W[pq];B[pr]
C[Now there are two ways to make two eyes so Black lives,]
(;W[ns];B[sr])
(;W[sr];B[ns];W[qr]
C[Wedging in does not take this eye away.];B[qq]))
(;W[ns];B[sr];W[qq];B[qr])
(;W[sr];B[ns];W[qq];B[qr])
(;W[qq];B[qr];W[sr];B[ns]))
(;B[pr];W[qq];B[qr];W[sr];B[ns];W[ps])
(;B[ns];W[pr];B[pq];W[qq])
(;B[qr];W[pq];B[pr];W[sr])
(;B[qq];W[sr]
(;B[pr];W[ns])
(;B[pq];W[ns])
(;B[ps];W[pq];B[pr];W[ns])
(;B[ns];W[pr];B[pq];W[ps])))

