proposition: Lemma ge0_cp x : 0 <= x -> (- x <= 0) * (- x <= x).
proof: Proof. by move=> hx; rewrite oppr_cp0 hx (@le_trans _ _ 0) ?oppr_cp0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(ssrAC div fintype path bigop order finset fingroup) mathcomp(ssralg poly)