(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play]C[Just play through the moves to move 20 which is the problem position. These do not represent a game sequence!]
;B[sr]
;W[rr]
;B[rq]
;W[qr]
;B[qq]
;W[pr]
;B[or]
;W[pq]
;B[oq]
;W[op]
;B[pp]
;W[oo]
;B[qp]
;W[po]
;B[qo]
;W[qn]
;B[np]
;W[ro]
;B[mq]
;W[pm]C[This is the problem position. Black to play.]
(;B[ps]
;W[rp]
;B[sq]
;W[sp]C[Black cannot win this race to capture.])
(;B[rs]
;W[rp]
;B[sq]
;W[sp]C[Nor this one,])
(;B[sq]
;W[sp]
;B[rs]
;W[rp]C[Nor even this one.])
(;B[sp]
;W[rp]
;B[sq]
;W[so]C[And this move failes too.])
(;B[rn]C[Correct: this is the tesuji.]
(;W[rp]
;B[sq]C[White cannot atari the 6 black stones without
being captured]
(;W[rm]
;B[rs]
;W[sn]
;B[ps]
;W[sp]C[Now having to waste time capturing the cutting stone
white is a move behind in the race.])
(;W[rs]
;B[ps]C[Still white cannot safely atari the blacks.]))
(;W[rm]
;B[rs]
;W[rp]
;B[sq]C[Still white cannot atari]
;W[sn]
;B[ps]C[And loses the race again.])))
