proposition: Lemma covered_byP C P I D A : C I D -> P I D A -> covered_by C P (\bigcup_(i in D) A i).
proof: Proof. by move=> CID PIDA; exists I, D, A. Qed.
imports: mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality fsbigop ) reals ereal signed topology normedtype sequences esum numfun HB(structures)