fact: Variable CSB : forall (X Y : Type) (f : X -> Y) (g : Y -> X), injective f -> injective g -> exists h : X -> Y, bijective h.
imports: Coq(FunctionalExtensionality Lia PeanoNat ProofIrrelevance ProofIrrelevanceFacts) ZornsLemma(FiniteTypes FunctionProperties) Coq(RelationClasses)