proposition: Lemma finI_from_cover (I : choiceType) T (D : set I) (f : I -> set T) : \bigcup_(A in finI_from D f) A = setT.
proof: Proof. rewrite predeqE => t; split=> // _; exists setT => //. by exists fset0 => //; rewrite set_fset0 bigcap_set0. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed