proposition: Lemma real_exprn_even_lt0 n x : x \is real -> ~~ odd n -> (x ^+ n < 0) = false.
proof: Proof. by move=> xR n_even; rewrite le_gtF // real_exprn_even_ge0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)