let am, bm, cm, dm, cin be set ; InnerVertices (BitFTA3Str (am,bm,cm,dm,cin)) is Relation
set S1 = BitGFA3Str (am,bm,cm);
set A1 = GFA3AdderOutput (am,bm,cm);
set S2 = BitGFA3Str ((GFA3AdderOutput (am,bm,cm)),cin,dm);
( InnerVertices (BitGFA3Str (am,bm,cm)) is Relation & InnerVertices (BitGFA3Str ((GFA3AdderOutput (am,bm,cm)),cin,dm)) is Relation )
by GFACIRC1:128;
hence
InnerVertices (BitFTA3Str (am,bm,cm,dm,cin)) is Relation
by FACIRC_1:3; verum