proposition: Fact prime_gcd p q : prime p -> is_gcd p q 1 \/ p <d q.
proof: Proof. intros H. generalize (gcd p q) (gcd_spec p q); intros g Hg. destruct (proj2 H _ (proj1 Hg)); subst; auto. right; apply Hg. Qed.
imports: List Arith Lia Bool Permutation Undecidability.Shared.Libs.DLW.Utils(utils_tac utils_list utils_nat gcd sums)