reserve x,y,z,c for object,
  f for Function of 2-tuples_on BOOLEAN, BOOLEAN;

theorem Th58:
  InnerVertices 2GatesCircStr(x,y,c,f) is Relation
proof
  InnerVertices 2GatesCircStr(x,y,c,f) = {[<*x,y*>, f], 2GatesCircOutput(x
  ,y,c,f)} by Th56;
  hence thesis;
end;
