proposition: Lemma eq_cardinal_ens_sym {A B : Type} (U : Ensemble A) (V : Ensemble B) : eq_cardinal_ens U V -> eq_cardinal_ens V U.
proof: Proof. apply eq_cardinal_ens_sym_dec. - apply classic. - intros ?. apply classic. Qed.
imports: Coq(ClassicalChoice Description Lia PeanoNat Program.Subset) ZornsLemma(Cardinals CountableTypes CSB DecidableDec Families Finite_sets FiniteTypes FunctionProperties FunctionPropertiesEns InverseImage Powerset_facts Proj1SigInjective ReverseMath.AddSubtract) Coq(RelationClasses)