let x, y, z be set ; :: thesis: for s being State of (GFA2CarryCirc (x,y,z))
for a1, a2, a3 being Element of BOOLEAN st a1 = s . x & a2 = s . y & a3 = s . z holds
( (Following s) . [<*x,y*>,and2a] = ('not' a1) '&' a2 & (Following s) . [<*y,z*>,and2c] = a2 '&' ('not' a3) & (Following s) . [<*z,x*>,nor2] = ('not' a3) '&' ('not' a1) )

set f1 = and2a ;
set f2 = and2c ;
set f3 = nor2 ;
let s be State of (GFA2CarryCirc (x,y,z)); :: thesis: for a1, a2, a3 being Element of BOOLEAN st a1 = s . x & a2 = s . y & a3 = s . z holds
( (Following s) . [<*x,y*>,and2a] = ('not' a1) '&' a2 & (Following s) . [<*y,z*>,and2c] = a2 '&' ('not' a3) & (Following s) . [<*z,x*>,nor2] = ('not' a3) '&' ('not' a1) )

set xy = [<*x,y*>,and2a];
set yz = [<*y,z*>,and2c];
set zx = [<*z,x*>,nor2];
let a1, a2, a3 be Element of BOOLEAN ; :: thesis: ( a1 = s . x & a2 = s . y & a3 = s . z implies ( (Following s) . [<*x,y*>,and2a] = ('not' a1) '&' a2 & (Following s) . [<*y,z*>,and2c] = a2 '&' ('not' a3) & (Following s) . [<*z,x*>,nor2] = ('not' a3) '&' ('not' a1) ) )
assume that
A1: a1 = s . x and
A2: a2 = s . y and
A3: a3 = s . z ; :: thesis: ( (Following s) . [<*x,y*>,and2a] = ('not' a1) '&' a2 & (Following s) . [<*y,z*>,and2c] = a2 '&' ('not' a3) & (Following s) . [<*z,x*>,nor2] = ('not' a3) '&' ('not' a1) )
set S = GFA2CarryStr (x,y,z);
A4: InnerVertices (GFA2CarryStr (x,y,z)) = the carrier' of (GFA2CarryStr (x,y,z)) by FACIRC_1:37;
A5: y in the carrier of (GFA2CarryStr (x,y,z)) by Th79;
A6: x in the carrier of (GFA2CarryStr (x,y,z)) by Th79;
A7: dom s = the carrier of (GFA2CarryStr (x,y,z)) by CIRCUIT1:3;
[<*x,y*>,and2a] in InnerVertices (GFA2CarryStr (x,y,z)) by Th80;
hence (Following s) . [<*x,y*>,and2a] = and2a . (s * <*x,y*>) by A4, FACIRC_1:35
.= and2a . <*a1,a2*> by A1, A2, A7, A6, A5, FINSEQ_2:125
.= ('not' a1) '&' a2 by TWOSCOMP:def 2 ;
:: thesis: ( (Following s) . [<*y,z*>,and2c] = a2 '&' ('not' a3) & (Following s) . [<*z,x*>,nor2] = ('not' a3) '&' ('not' a1) )
A8: z in the carrier of (GFA2CarryStr (x,y,z)) by Th79;
[<*y,z*>,and2c] in InnerVertices (GFA2CarryStr (x,y,z)) by Th80;
hence (Following s) . [<*y,z*>,and2c] = and2c . (s * <*y,z*>) by A4, FACIRC_1:35
.= and2c . <*a2,a3*> by A2, A3, A7, A5, A8, FINSEQ_2:125
.= a2 '&' ('not' a3) by Def3 ;
:: thesis: (Following s) . [<*z,x*>,nor2] = ('not' a3) '&' ('not' a1)
[<*z,x*>,nor2] in InnerVertices (GFA2CarryStr (x,y,z)) by Th80;
hence (Following s) . [<*z,x*>,nor2] = nor2 . (s * <*z,x*>) by A4, FACIRC_1:35
.= nor2 . <*a3,a1*> by A1, A3, A7, A6, A8, FINSEQ_2:125
.= ('not' a3) '&' ('not' a1) by TWOSCOMP:54 ;
:: thesis: verum