fact: Definition eq_cardinal_ens {A B : Type} (U : Ensemble A) (V : Ensemble B) : Prop := ((B -> False) /\ forall a : A, ~ In U a) \/ exists f : A -> B, range f U V /\ bijective_ens f U V.
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)