(;GM[1]FF[4]SZ[19]
GN[Very difficult ko]
PC[http://senseis.xmp.net/?GokyoSeimyoVolume3Problem2/Attempts]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?GokyoSeimyoVolume3Problem2/Attempts

Very difficult ko]
PL[B]

AB[fb][bc][dc][ec][fc][cd][ce][ee][df]
AW[cb][db][eb][cc][bd][be][cf][cg]

;B[bb]C[B1]MN[1]
;W[ba]C[W2]MN[2]
;B[ab]C[B3]MN[3]
;W[fa]C[W4]MN[4]
;B[ga]C[B5]MN[5]
;W[da]C[W6]MN[6]

;
)
