fact: Definition least_cardinal (P : forall {X : Type} (U : Ensemble X), Prop) {X : Type} (U : Ensemble X) : Prop := P U /\ (forall (Y : Type) (V : Ensemble Y), P V -> le_cardinal_ens 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)