The Clowder Project

Question 9.7.3.1.3. [Characterisations of Functors With Epic Pre/Postcomposition]
Is there a characterisation of functors $F\colon \mathcal{C}\to \mathcal{D}$ such that:

1. For each $\mathcal{X}\in \text{Obj}\webleft (\mathsf{Cats}\webright )$, the precomposition functor
   \[ F^{*}\colon \mathsf{Fun}\webleft (\mathcal{D},\mathcal{X}\webright )\to \mathsf{Fun}\webleft (\mathcal{C},\mathcal{X}\webright ) \]

   is an epimorphism of categories?

2. For each $\mathcal{X}\in \text{Obj}\webleft (\mathsf{Cats}\webright )$, the postcomposition functor
   \[ F_{*}\colon \mathsf{Fun}\webleft (\mathcal{X},\mathcal{C}\webright )\to \mathsf{Fun}\webleft (\mathcal{X},\mathcal{D}\webright ) \]

   is an epimorphism of categories?

This question also appears as [MO 468125].