Hint Resolve eqm_trans: ints.

(* Specifications: *)
Lemma eqm_small_eq:
forall x y, eqm x y -> 0 <= x < modulus -> 0 <= y < modulus -> x = y.
Lemma eqm_small_eq:
forall x y, eqm x y -> 0 <= x < modulus -> 0 <= y < modulus -> x = y.