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(********** in order to bound Domain and Range we first ********)
(********** define  Total   ***********)

Definition UnionPlus (F : Ens) := union F (Union F).Definition Total (R : Ens) := UnionPlus (UnionPlus (UnionPlus R)).

Theorem Total_th4 : forall (X Y Z W F : Ens) (i : IN X Y) (j : IN Y Z) (k : IN Z W) (l : IN W F), IN X (Total F).