(;GM[1]FF[4]SZ[19]CA[utf-8]AP[SmartGo One:1.6.7]GN[205dx]AB[qp][rp][sp][kq][lq][pq][pr][qq][mr][nr][os]AW[mo][po][qo][ro][so][lp][op][oq][or][pp][mq][nq][rq][rr][qr]C[Black to play.]
(;B[lr]C[If Black defends this weakness White lives.];W[sq];B[ps];W[qs];B[ns];W[ss])
(;B[ps]C[Black should defend here instead.];W[qs]
(;B[rs]C[Black has to play here to stop the forcing plays that let White live.];W[ss]
;B[sq]C[Now White is short of liberties and dead in the corner.])
(;B[ns]C[If Black plays here White can live.];W[sq];B[lr];W[ss])
(;B[lr]C[Also White lives.];W[sq];B[ns];W[ss])
(;B[sr]C[This leads to a ko.];W[ss];B[rs];W[lr];B[kr];W[ss]
(;B[ns]C[This lets White win the ko and live.];W[sq];B[ls])
(;B[pm]C[Black must play a threat to win the ko.];W[pl];B[rs])))
(;B[rs]C[This is wrong.]
(;W[sq];B[ps];W[ss]
;B[sr]C[White gets a ko.])
(;W[qs]C[This is a mistake by White.];B[ps];W[ss];B[sq]))
(;B[sr]C[This is also wrong.]
(;W[qs];B[sq];W[ss]
;B[rs]C[Again White can get a ko.])
(;W[sq]C[This is a mistake by White.];B[ps];W[ss];B[qs]))
(;B[qs]C[This fails as Black runs out of liberties.];W[sq];B[ps];W[rs])
(;B[ns]C[This also too kind to White.]
(;W[sq];B[ps];W[qs];B[lr];W[ss])
(;W[qs]
(;B[ps];W[sq];B[lr];W[ss])
(;B[sr];W[ps]))))
