proposition: Lemma lte_subr_addr x y z : z \is a fin_num -> (x < y - z) = (x + z < y).
proof: Proof. move: x y z => [x| |] [y| |] [z| |] _ //=; rewrite ?ltNyr ?ltry //. by rewrite !lte_fin ltrBrDr. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed