public static Proposition createImpliesProposition(Stella_Object tail, Stella_Object head) {
    { Proposition impliesprop = Logic.createProposition(Logic.SYM_LOGIC_IMPLIES, 2);

      (impliesprop.arguments.theArray)[0] = (Logic.maybeSubstituteSurrogateArgument(tail, head));
      (impliesprop.arguments.theArray)[1] = (Logic.maybeSubstituteSurrogateArgument(head, tail));
      Proposition.verifyArgumentTypesAndCount(impliesprop);
      return (impliesprop);
    }
  }