(bind-func xtm_equal
  (lambda (a:Rational b:Rational)
    (let ((reduced_a (Rational_reduce a))
          (reduced_b (Rational_reduce b)))
      (and (= (tref reduced_a 0)
              (tref reduced_b 0))
           (= (tref reduced_a 1)
              (tref reduced_b 1))))))