(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PW[]PB[Black to Play]
;B[pq]C[Just play through the moves to move 28 which is the problem
position. These do not represent a game sequence!]
;W[pr]
;B[qr]
;W[or]
;B[ps]
;W[qq]
;B[rq]
;W[qp]
;B[rr]
;W[pp]
;B[oq]
;W[nq]
;B[op]
;W[oo]
;B[np]
;W[mq]
;B[no]
;W[ns]
;B[rp]
;W[mn]
;B[rn]
;W[om]
;B[]
;W[pm]
;B[]
;W[qm]
;B[]
;W[mr]C[This is the problem position. Black to play
and capture the cutting white stones.]
(;B[pn]C[CORRECT: This is the key move. An effective double peep,
one at the cut below and one at the cut to its left.
Whatever white tries now he cannot link the 
three stones up to the line of three at the top.
Fighting the semeai (capturing race) againt
the five black stones to the left doesn't work as
they have three libeties and the three white stones 
only two. ]
(;W[po]
;B[on]
;W[qo]
;B[qn])
(;W[on]
;B[po]
;W[qo]
;B[qn])
(;W[qn]
;B[qo]
;W[po]
;B[on]))
(;B[po]C[FAILURE]
;W[qo]C[This fails white can link up by atari on the black stone.]
;B[pn]
;W[qn])
(;B[qo]C[FAILURE]
;W[po]C[Here white makes a connection through the bamboo joint.])
(;B[on]C[FAILURE. This one is hardest for white to get right]
;W[pn]
;B[po]
;W[qo]
;B[qn]
;W[oo]C[It ends in Ko with black to find the first ko threat,
so hardly a success!]))
