proposition: Lemma ler_nXz2r n (hn : n < 0) : {in > 0 & , {mono ((@exprz R)^~ n) : x y /~ x <= y}}.
proof: Proof. apply: le_nmono_in (inj_nhomo_lt_in _ _); last first. by apply: ler_wnXz2r; rewrite ltW. by move=> x y hx hy /=; apply: pexpIrz; rewrite ?[_ \in _]ltW ?lt_eqF. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)