set f = xor2 ;
let x, y, z be set ; :: thesis: ( z <> [<*x,y*>,xor2] implies for s being State of (GFA3AdderCirc (x,y,z))
for a1, a2, a3 being Element of BOOLEAN st a1 = s . x & a2 = s . y & a3 = s . z holds
( (Following (s,2)) . (GFA3AdderOutput (x,y,z)) = (a1 'xor' a2) 'xor' a3 & (Following (s,2)) . [<*x,y*>,xor2] = a1 'xor' a2 & (Following (s,2)) . x = a1 & (Following (s,2)) . y = a2 & (Following (s,2)) . z = a3 ) )
assume A1: z <> [<*x,y*>,xor2] ; :: thesis: for s being State of (GFA3AdderCirc (x,y,z))
for a1, a2, a3 being Element of BOOLEAN st a1 = s . x & a2 = s . y & a3 = s . z holds
( (Following (s,2)) . (GFA3AdderOutput (x,y,z)) = (a1 'xor' a2) 'xor' a3 & (Following (s,2)) . [<*x,y*>,xor2] = a1 'xor' a2 & (Following (s,2)) . x = a1 & (Following (s,2)) . y = a2 & (Following (s,2)) . z = a3 )
set O0 = GFA0AdderOutput (x,y,z);
set O3 = GFA3AdderOutput (x,y,z);
set A0 = GFA0AdderCirc (x,y,z);
set A3 = GFA3AdderCirc (x,y,z);
( GFA3AdderCirc (x,y,z) = GFA0AdderCirc (x,y,z) & GFA3AdderOutput (x,y,z) = GFA0AdderOutput (x,y,z) ) ;
hence for s being State of (GFA3AdderCirc (x,y,z))
for a1, a2, a3 being Element of BOOLEAN st a1 = s . x & a2 = s . y & a3 = s . z holds
( (Following (s,2)) . (GFA3AdderOutput (x,y,z)) = (a1 'xor' a2) 'xor' a3 & (Following (s,2)) . [<*x,y*>,xor2] = a1 'xor' a2 & (Following (s,2)) . x = a1 & (Following (s,2)) . y = a2 & (Following (s,2)) . z = a3 ) by A1, Th30; :: thesis: verum