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7 votes
0 answers
385 views

When is the character group scheme of a group scheme representable? (Affine Case)

While reading Tate's article on Finite Flat Group Schemes in "Modular Forms and Fermat's Last Theorem" I was lead to this question. Let $S$ be a scheme, $G$ a group scheme over $S$, and $T$ an $S$-...
J. David Taylor's user avatar
5 votes
0 answers
94 views

$\text{Rep}(D_4)$ and its three fiber functors

It is well-known that the fusion category $\text{Rep}(D_4)$ of representations of the dihedral group $D_4$ of order 8 admits three distinct fiber functors. Therefore, there are three different Hopf ...
Alonso Perez-Lona's user avatar
5 votes
0 answers
172 views

Are the symmetric groups integrable as Hopf algebras?

Let $G$ be a group. For $g,h \in G$, let $[g,h]=g^{-1}h^{-1}gh$ be a commutator. The normal subgroup $G' = \langle [g,h] \ | \ g,h \in G \rangle$ is called the commutator subgroup or derived subgroup. ...
Sebastien Palcoux's user avatar
4 votes
0 answers
67 views

Is the associated grouplike $\gamma=uS(u)^{-1}$ of a quasi-triangular Hopf algebra always the square of another grouplike?

Let $(H,R)$ be a finite-dimensional quasi-triangular Hopf algebra, lets say generated by group-like and skew-primitive elements (I actually need it for $H$ fin. dim. pointed with $G(H)$ abelian). Let $...
Bipolar Minds's user avatar
3 votes
0 answers
325 views

Intuitive, elementary intros to Hopf algebras/monoids

Motivation: I'm interested in understanding the role that noncrossing partitions play in Hopf algebras/monoids (HAs) as the components of the power series of the compositional inverse of formal ...
Tom Copeland's user avatar
  • 10.5k
3 votes
0 answers
122 views

It there a nice way to describe the structure of Malcev-complete groups?

Let $\mathbb k$ be a field of characteristic zero. The grouplike functor $\mathbb G$ from complete Hopf algebras to groups is a faithful functor. Its image is the category of Malcev-complete groups ...
J. Darné's user avatar
  • 273
3 votes
0 answers
515 views

What happens geometrically when you take associated-graded (or complete, ...) of a group ring at its augmentation ideal?

I am interested in the following functor from Monoids (in $\text{Set}$) to Graded Lie Algebras (over a fixed field of characteristic $0$). (By "graded" I mean only that my Lie algebras have some ...
Theo Johnson-Freyd's user avatar