proposition: Lemma Rhull0 : Rhull set0 = `]0, 0[ :> interval R.
proof: Proof. rewrite /Rhull (asboolT (has_lbound0 R)) (asboolT (has_ubound0 R)) asboolF //. by rewrite sup0 inf0. Qed.
imports: HB(structures) mathcomp(all_ssreflect ssralg ssrint ssrnum finmap matrix) mathcomp(rat interval zmodp vector fieldext falgebra) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality set_interval Rstruct) ereal reals signed topology prodnormedzmodule