(;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[qn][rn][pp][pq][rq][or][pr][rr][ps]AB[pn][no][po][qo][ro][op][rp][oq][nr][ns][os]
(;B[sq]C[The correct way to kill here is to restric the eyespace first...]
(;W[sr]
;B[rs]C[... and then play the vital point inside.]
(;W[qs]C[It looks like this will make two eyes...]
(;B[qq]C[... but this wedge catches white short of liberties.]
(;W[qp]C[Self-atari!])
(;W[qr]
;B[qp]C[One eye.]))
(;B[qp]
;W[qq]C[Just pushing is no good. White makes two eyes.]))
(;W[qp]C[If white maximises his eye space.]
;B[qr]C[... then this wedge leaves white short again.]
(;W[qq]
;B[qs]C[Dead shape.])
(;W[qs]C[Self-atari.])
(;W[ss]C[Also self-atari.]))
(;W[qq]C[Clearly all other white moves here are easy to kill.]
;B[qs]))
(;W[qp]C[All other white moves only make one eye]
;B[sr]
;W[rs]
;B[qr])
(;W[qs]
;B[sr]))
(;B[qq]C[Playing the wedge first is no good.]
;W[qp]
;B[sq]
;W[sr]
;B[rs]
;W[qr])
(;B[rs]C[Nor does playing the second move first.]
;W[sq]
;B[qq]
;W[qp]))
