(;GM[1]FF[4]SZ[19]
GN[B3 and B5 are Black's ko threat, W8 is at BC]
PC[http://senseis.xmp.net/?HolIgorExploresYoseProblem1]AP[GoWiki:2009]
DT[2018-10-15]
C[Diagram from http://senseis.xmp.net/?HolIgorExploresYoseProblem1

B3 and B5 are Black's ko threat, W8 is at BC]
PL[B]

AB[ab][bc][bd][be][ce][de][df][ef]
AW[ca][bb][db][eb][gb][cc][ec][cd][dd][ee][fe]
CR[ab]

;B[ba]C[B1]MN[1]
;W[aa]C[W2]MN[2]
;W[ac]C[W4]MN[4]
;W[ad]C[W6]MN[6]
;B[ae]C[B7]MN[7]

;CR[ab]
)
