`{!IsSurjInj G, !IsSurjInj (G o F)} : IsSurjInj F. Proof. constructor. - apply cancelL_isesssurj. - intros x y f. exact (essinj (G o F) (fmap G f)). Defined.
Require Import Basics.Overture Basics.Tactics Basics.Iff. Require Import WildCat.Core. Require Import WildCat.NatTrans. Require Import WildCat.Sigma.