intros A f r; unfold INC in |- *; simpl in |- *.
intros E'; simple induction 1; intros P.
elim E'; simpl in |- *.
intros A' f' r'.
simple induction 1; intros HA HB.
intros E''; simple induction 1; intros a' e.
elim (HA a').
simple induction x; intros a p.
intros; exists a.
auto with zfc.
apply EQ_tran with (f' a'); auto with zfc.
Qed.

Theorem INC_IN_Power : forall E E' : Ens, INC E' E -> IN E' (Power E).
simple induction E; intros A f r; unfold INC in |- *; simpl in |- *.