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(* Prelude *)
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(* export inj_pair without exporting the whole Eqdep library *)
Definition inj_pair2 := @inj_pair2.(* eta laws for pairs and units *)
Notation prod_eta := surjective_pairing.

Lemma compA A B C D (h : A -> B) (g : B -> C) (f : C -> D) : (f \o g) \o h = f \o (g \o h).