proposition: Lemma cvg_in_ex {U : Type} (T : filteredType U) (F : set_system U) : [cvg F in T] <-> (exists l : T, F --> l).
proof: Proof. by split=> [cvg|/getPex//]; exists [lim F in T]. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed