proposition: Lemma itv_ge0 x : unify_itv `[Posz 0, +oo[ i -> 0%R <= x%:inum :> R.
proof: Proof. move: x => [x /= xi] /(@Itv.subitv_map_itv R) /subitvP /(_ _ xi). by rewrite in_itv/= andbT. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool) mathcomp(ssrnat eqtype choice order ssralg ssrnum ssrint) mathcomp(interval) mathcomp(mathcomp_extra boolp) signed