(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play]AW[lq][mq][nq][oq][kr][nr][pr][qr]AB[jp][lp][mp][np][op][kq][pq][qq][rq][jr][or][rr]C[This is the problem position. Black to play]
(;B[lr]C[This traps one stone, but only one.]
;W[os]
(;B[ms]
;W[mr]
;B[ks]
;W[qs]C[White can make two eyes.])
(;B[qs]C[White can still make the eye the other side if black here.]
;W[ms]
;B[ks]
;W[ls]
;B[kr]
;W[mr]
;B[rs]
;W[ps]))
(;B[os]C[Sometimes drawing out the trapped stone,
following the proverb "never sacrifice just one stone",
is the key move.]
;W[ls]
;B[qs]
;W[ns]
;B[ps]
;W[mr]C[But white black is capturing two stones, white
is making two eyes.])
(;B[ks]C[The key for destroying the eyes is actually the edge atari.
This is the correct move.]
(;W[lr]C[If white connects...]
;B[os]C[... black now draw out the trapped stone.]
;W[ns]
;B[ls]
(;W[ms]
;B[mr])
(;W[ps]
;B[ms]C[Only one eye.]))
(;W[os]C[If white removes the aji of the trapped stone.]
;B[ms]C[This is then the tesuji taking away the left eye
and threatening to make the centre eye false
if black makes the right eye.]
(;W[qs]
;B[ns])
(;W[ns]
;B[qs]))))
