proposition: Lemma neitv_Rhull A : ~~ neitv (Rhull A) -> A = set0.
proof: Proof. move/negPn/eqP => A0; rewrite predeqE => r; split => // /sub_Rhull. by rewrite A0. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum ssrint interval) mathcomp(finmap fingroup perm rat) mathcomp(mathcomp_extra boolp classical_sets functions) HB(structures) reals ereal signed topology normedtype sequences