proposition: Lemma ge0_funenegE f : (forall x, D x -> 0 <= f x) -> {in D, f^\- =1 cst 0}.
proof: Proof. by move=> f0 x; rewrite inE => Dx; apply/max_idPr; rewrite leeNl oppe0 f0. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrnum ssrint interval finmap) mathcomp(mathcomp_extra boolp classical_sets fsbigop) mathcomp(functions cardinality set_interval) signed reals ereal topology normedtype sequences