proposition: Lemma lee_lt_add a b x y : a \is a fin_num -> a <= x -> b < y -> a + b < x + y.
proof: Proof. by move=> afin xa yb; rewrite (addeC a) (addeC x) lte_le_add. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed