(;GM[1]FF[4]CA[UTF-8]AP[CGoban:3]ST[2]
RU[Japanese]SZ[19]KM[0.00]
PB[Black to play]AW[do][bp][cp][ep][bq][eq][fq][gq][gr][gs]AB[cq][ar][br][cr][fr][cs][es][fs]C[This is the problem position. Black to play.]
(;B[dr]C[If black tries to make two eyes this way...]
;W[er]C[... he clearly fails.])
(;B[dq]C[This move fails too.]
;W[er])
(;B[er]C[So this one must be the correct move.]
(;W[dq]C[This is too easy for black to live (but may be the best
move for white as it makes 1 point of territory in sente).]
;B[dr]C[Black makes 3 points of territory and white 1,
so this is 2 points net to black.])
(;W[dr]C[This is the tricky move as black is in atari.]
(;B[ds]
;W[dq]C[This is clearly dead.])
(;B[dq]C[Black plays here and it looks like he has missed
the four stones in atari.]
;W[ds]C[White takes....]
;B[er]C[... but black plays back where the stones used to be - 
a technique called "under the stones".]
(;W[es]
;B[fs]C[Now white cannot stop black from living.])
(;W[fr]
;B[es]C[Black still alive. Black had 4 stones captured,
white 2 and black makes 4 points of territory, 
so black ends with 2 points net (the same 
as if white had simply forced black to make 2 eyes,
but white has worse shape). ])))))
