proposition: Lemma open_bigcup_ointsub U q : open (bigcup_ointsub U q).
proof: Proof. by apply: bigcup_open => i [[]]. 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