(;GM[1]FF[4]SZ[19]
GN[Refutation]
PC[http://senseis.xmp.net/?BeginnerExercise107/Attempts]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?BeginnerExercise107/Attempts

Refutation]
PL[W]

AB[da][db][ac][bc][cc]
AW[ea][eb][ec][ad][bd][cd][dd]

;W[dc]C[W1]MN[1]
;B[ba]C[B2]MN[2]

;
)
