Timeline for What is the opposite category of the category of modules (or Hopf algebra representations)?
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| Aug 11, 2012 at 21:55 | comment | added | Peter Arndt | @DavidWhite: 1. Yes, you need more than one object, G is just one generating object. 2. My answer was only about the first part, not about the Hopf algebra part. I don't think H-mod is locally presentable; it seems that you need more than just finite limits to describe that structure. | |
| Jul 27, 2012 at 14:40 | comment | added | David White | How does this theorem of Adamek and Rosicky relate to Ryan Reich's answer? If $H$ is a Hopf algebra, is $H-mod$ a locally finitely presentable category? Seems like it should be, since I can write down all its defining properties via commutative diagrams. But $(H-mod)^{opp} \cong (H-mod)$ so that seems to contradict the theorem. What am I missing? | |
| Jul 27, 2012 at 14:38 | comment | added | David White | Just to clarify: the limit sketch of groups needs to have more than just one object, right? It should have $G$, $G\times G$, $G\times G\times G$, etc. Otherwise I don't understand how you have a map in that category from $G\times G\rightarrow G$. | |
| Sep 25, 2010 at 21:38 | history | answered | Peter Arndt | CC BY-SA 2.5 |