proposition: Lemma lteNl x y : (- x < y) = (- y < x).
proof: Proof. by move: x y => [r| |] [r'| |] //=; rewrite ?(ltry, ltNyr)// !lte_fin ltrNl. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra) signed