set f1 = and2b ;
set f2 = and2b ;
set f3 = and2b ;
set f4 = nor3 ;
let x, y, z be set ; :: thesis: InnerVertices (GFA3CarryStr x,y,z) is Relation
set xy = [<*x,y*>,and2b ];
set yz = [<*y,z*>,and2b ];
set zx = [<*z,x*>,and2b ];
set Cxy = 1GateCircStr <*x,y*>,and2b ;
set Cyz = 1GateCircStr <*y,z*>,and2b ;
set Czx = 1GateCircStr <*z,x*>,and2b ;
set Cxyz = 1GateCircStr <*[<*x,y*>,and2b ],[<*y,z*>,and2b ],[<*z,x*>,and2b ]*>,nor3 ;
A1: ( InnerVertices (1GateCircStr <*x,y*>,and2b ) is Relation & InnerVertices (1GateCircStr <*y,z*>,and2b ) is Relation & InnerVertices (1GateCircStr <*z,x*>,and2b ) is Relation ) by FACIRC_1:38;
then InnerVertices ((1GateCircStr <*x,y*>,and2b ) +* (1GateCircStr <*y,z*>,and2b )) is Relation by FACIRC_1:3;
then ( InnerVertices (1GateCircStr <*[<*x,y*>,and2b ],[<*y,z*>,and2b ],[<*z,x*>,and2b ]*>,nor3 ) is Relation & InnerVertices (GFA3CarryIStr x,y,z) is Relation ) by A1, FACIRC_1:3, FACIRC_1:38;
hence InnerVertices (GFA3CarryStr x,y,z) is Relation by FACIRC_1:3; :: thesis: verum