(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play]AW[lo][mo][no][oo][po][lp][qp][lq][mq][pq][qq][lr][qr][ms][ns][os][qs]AB[qn][qo][kp][pp][rp][kq][rq][kr][mr][nr][rr][ks][ls][rs]C[Does White need to defend?]
(;B[or]C[If Black plays this atari...]
;W[ps]
;B[oq]
;W[op]C[... then White is alright])
(;B[oq]C[This looks like a vital point.]
;W[op]C[However White is safe if this capture is made.]
(;B[ps]
;W[pr]
;B[or]C[Black is short of liberties.]
;W[nq])
(;B[or]C[This doesn't work either.]
;W[ps]
;B[pr]
;W[nq]))
(;B[ps]C[However Black can start with the throw-in, so White should have defended.]
(;W[pr]C[If White captures...]
;B[or]C[... White is now short of liberties not Black.]
;W[ps]
;B[oq])
(;W[or]C[White plays this, it is atari on two black stones.]
;B[oq]C[However this is double atari and White is defenceless.]
(;W[nq]
;B[pr])
(;W[op]
;B[pr])
(;W[pr]
;B[ps]))
(;W[oq]C[White should now just play here and give up the three edge stones.])))
