Section Eeq1.
Variables I X Y Z: Type.
Variable R' R1': relation2 X Y.
Variable S': relation2 Y Z.
Variable R  R1: relation2 X Y.
Variable S : relation2 Y Z.
Variables T' T: relation X.
Variables F' F: I -> relation2 X Y.

Lemma union_incl: (forall i, incl (F i) (F' i)) -> incl (union F) (union F').