proposition: Lemma eq_of_le_le {a b : nat} (le_a_b : a ≤ b) (le_b_a : b ≤ a) : a = b.
proof: Proof. destruct (natlehchoice _ _ le_a_b) as [lt_a_b | e_a_b]. 2: { assumption. } apply fromempty. eapply natlthtonegnatgeh; eassumption. Qed.
imports: UniMath.Foundations.All UniMath.MoreFoundations.All UniMath.Combinatorics.Maybe UniMath.Combinatorics.StandardFiniteSets UniMath.Algebra.Domains_and_Fields UniMath.Algebra.RigsAndRings