
theorem
  for x,y,z being set holds InnerVertices BitGFA2Str(x,y,z) is Relation
proof
  let x,y,z be set;
  set S1 = GFA2AdderStr(x,y,z);
  set S2 = GFA2CarryStr(x,y,z);
  InnerVertices S1 is Relation & InnerVertices S2 is Relation by Th75,
FACIRC_1:58;
  hence thesis by FACIRC_1:3;
end;
