(M : IsInitialMorphism Ap) (Y : D) (f : morphism C X (U Y)) : morphism D (IsInitialMorphism_object M) Y := CommaCategory.
Require Import Category.Core Functor.Core. Require Import Category.Dual Functor.Dual. Require Import Category.Objects. Require Import InitialTerminalCategory.Core InitialTerminalCategory.Functors. Import Comma.Core. Require Import Trunc Types.Sigma HoTT.Tactics. Require Import Basics.Tactics.