let x, y, z be set ; :: thesis: InnerVertices (BitGFA0Str x,y,z) is Relation
set S1 = GFA0AdderStr x,y,z;
set S2 = GFA0CarryStr x,y,z;
( InnerVertices (GFA0AdderStr x,y,z) is Relation & InnerVertices (GFA0CarryStr x,y,z) is Relation ) by Th15, FACIRC_1:58;
hence InnerVertices (BitGFA0Str x,y,z) is Relation by FACIRC_1:3; :: thesis: verum