(;GM[1]FF[4]SZ[19]
GN[1-2 principle]
PC[http://senseis.xmp.net/?ReversiblePlayLossAndGain]AP[GoWiki:2009]
DT[2009-04-22]
C[Diagram from http://senseis.xmp.net/?ReversiblePlayLossAndGain

1-2 principle]
PL[B]

AB[bb][db][dc][bd][dd]
AW[eb][ec][ed]

;B[ea]C[B1]MN[1]
;W[fa]C[W2]MN[2]
;W[da]C[W4]MN[4]
;B[ca]C[B5]MN[5]
;W[fb]C[W8]MN[8]

;
)
