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Nov 4, 2018 at 9:57 comment added Adrien Note that while "being modules for an Hopf algebra" is an extra structure while "being modules for a quasi-Hopf algebra" is a property, which I think is preserved under formal deformations under reasonable assumptions...
Nov 4, 2018 at 9:12 comment added Adrien @NoahSnyder Drinfeld's paper deals with twist-equivalence classes of deformations of $U(\mathfrak g)$ as a (quasi-triangular-)quasi-Hopf algebra, so you're right it's not entirely obvious that it also classifies deformations as (braided) tensor categories, but I think at least for semi-simple $\mathfrak g$ this is the case.
Nov 4, 2018 at 8:55 comment added Adrien @VictorProtsak RIght, of course, I edited.
Nov 4, 2018 at 8:55 history edited Adrien CC BY-SA 4.0
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Nov 4, 2018 at 5:08 comment added Victor Protsak If $\mathfrak{g}$ is a semisimple Lie algebra with $k$ simple components then the space of invariant symmetric bilinear forms is $k$-dimensional, and the same is true for invariant symmetric 2-tensors. (One can independently rescale the Killing form on each component by its own scalar.)
Nov 3, 2018 at 22:18 comment added Noah Snyder Is this really deformations of the tensor category, or just of the Hopf algebra?
Nov 3, 2018 at 18:48 history edited Adrien CC BY-SA 4.0
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Nov 3, 2018 at 18:33 history answered Adrien CC BY-SA 4.0