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Jan 1, 2010 at 22:38 comment added Mike Shulman You can spell out the definition of homs in presheaf categories in terms of an end in Set, if you like: $G^F(c) = Hom(y(c)\times F, G) = \int_{c'} Hom(C(c,c')\times F(c'), G(c'))$. You could then invoke the construction of limits in Set, so that $G^F(c)$ is the set of tuples $(h_{c'})_{c'\in C}$, where $h_{c'}\colon C(c,c')\times F(c')\to G(c')$, such that for any $\gamma\colon c'\to c''$ in $C$ we have $G(\gamma) \circ h_{c'} = h_{c''} \circ (C(c,\gamma) \times F(\gamma))$.
Jan 1, 2010 at 22:28 vote accept Harry Gindi
Jan 1, 2010 at 22:28 comment added Harry Gindi Accepted and +1, but is there any way to obtain a more concrete description?
Jan 1, 2010 at 22:22 history answered Mike Shulman CC BY-SA 2.5