Definition EQC : Ens -> Ens -> Type.(* APPARTENANCE *)

Definition CIN : Ens -> Ens -> Type.(* INCLUSION *)

Definition CINC : Ens -> Ens -> Type.

Theorem tout_vide_est_VideC : forall E : Ens, (forall E' : Ens, CIN E' E -> F) -> EQC E Vide.