A functor $F\colon \mathcal{C}\to \mathcal{D}$ is corepresentably fully faithful on cores if, for each $X\in \operatorname {\mathrm{Obj}}\webleft (\mathsf{Cats}\webright )$, the postcomposition by $F$ functor
is fully faithful.
Let $\mathcal{C}$ and $\mathcal{D}$ be categories.
A functor $F\colon \mathcal{C}\to \mathcal{D}$ is corepresentably fully faithful on cores if, for each $X\in \operatorname {\mathrm{Obj}}\webleft (\mathsf{Cats}\webright )$, the postcomposition by $F$ functor
is fully faithful.
In detail, a functor $F\colon \mathcal{C}\to \mathcal{D}$ is corepresentably fully faithful on cores if it satisfies the conditions in Remark 11.8.7.1.2 and Remark 11.8.8.1.2, i.e.:
For all diagrams of the form
then $\alpha =\beta $.
For each $\mathcal{X}\in \operatorname {\mathrm{Obj}}\webleft (\mathsf{Cats}\webright )$ and each natural isomorphism
Is there a characterisation of functors corepresentably fully faithful on cores?