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2
votes
Is the category of spherical fusion categories regular? (i.e. is image factorisation possible?)
I think the following is true, and what I was looking for.
A tensor functor $F: \mathcal{C} \to \mathcal{D}$ is called dominant (sometimes called "surjective") if for any $Y: \mathcal{D}$, there is a …
2
votes
1
answer
136
views
Is the category of spherical fusion categories regular? (i.e. is image factorisation possible?)
Consider the category where objects are strict spherical fusion categories and morphisms are strict spherical functors (preserving cups and caps). I am wondering whether there is some kind of image fa …
3
votes
1
answer
170
views
Pivotal functors of that are substantially different from finite group homomorphisms
Fusion categories can be seen as generalisations of the representation category of finite groups. I'm interested in spherical fusion categories. I'm trying to find "interesting" functors from a spheri …
1
vote
Accepted
Pivotal functors of that are substantially different from finite group homomorphisms
I've been thinking about this since longer already and just realised a really easy example. I was a bit of a blockhead in thinking that for any inclusion functor $F$, we must have that $F\Omega_\mathc …
4
votes
0
answers
88
views
Are there any dominant pivotal functors such that the regular representation is not mapped o...
This question is related to Pivotal functors of that are substantially different from finite group homomorphisms.
A tensor functor $F: \mathcal{C} \to \mathcal{D}$ is called dominant (sometimes calle …
12
votes
1
answer
527
views
Is there a "killing" lemma for G-crossed braided fusion categories?
Edit: I found a serious flaw in the question and my answer, and I had to change a lot. The basic question is still there, but the details are a lot different.
Premodular categories
In braided spheri …
9
votes
2
answers
399
views
What is a true invariant of $G$-crossed braided fusion categories?
Definition. An invariant of a (spherical) fusion category with extra structure is a number or a set or tuple of numbers preserved under (appropriate) equivalences.
(Spherical) fusion categories have …
2
votes
Accepted
Is there a "killing" lemma for G-crossed braided fusion categories?
Edit:
I used to believe that there is a possible generalisation stemming from work of Altschüler and Bruguières. (See Appendix C in Drinfeld, Gelaki, Nikshych, Ostrik - On braided fusion categories I) …
5
votes
1
answer
302
views
Is every premodular category the *full* subcategory of a modular category?
In Müger's article "Conformal Field Theory and Doplicher-Roberts Reconstruction", he defines the "modular closure" of a braided monoidal category. So every braided monoidal category (and therefore eve …
5
votes
2
answers
1k
views
When is the endofunctor category of a monoidal category braided? When is it ribbon? Fusion? ...
Given a category $\mathcal{C}$, we can define the category of endofunctors $\operatorname{Cat}(\mathcal{C})$, with objects functors $F: \mathcal{C} \to \mathcal{C}$ and morphisms natural transformatio …
9
votes
1
answer
267
views
Is the modularisation of a unitary fusion category always unitary?
Suppose $\mathcal{C}$ is a unitary ribbon fusion category. Also assume that its symmetric centre has trivial twist and trivial pivotal structure, i.e. is tannakian. Thus, the Müger/Bruguières modulari …
2
votes
1
answer
152
views
How nontrivial can "central extensions of ribbon fusion categories" be?
In a sense, this is a follow up on this question, but one PhD programme later.
Let $\mathcal{C}$ be ribbon fusion. By $\mathcal{C}'$, we denote the symmetric centre, i.e. the full subcategory of obje …
8
votes
0
answers
679
views
What classifies involutive automorphisms on finite groups? What classifies involutions on fi...
Groups
Let $G$ be a finite group. An involutive automorphism on $G$ is an automorphism $i\colon G \to G$ such that $i^2 = 1_G$.
Question 1. What classifies involutive automorphisms on a given (non-a …
2
votes
1
answer
152
views
Modularisation on group representations with arbitrary braiding
Applying the modularisation/deequivariantisation procedure to the representation category $\operatorname{Rep}_G$ of a finite group $G$ with trivial braiding gives the fibre functor to vector spaces. W …
6
votes
1
answer
337
views
Is there a quotient or exact sequence of symmetric, premodular (ribbon fusion) and modular c...
In Walker and Wang's article about (3+1)-TQFTs from premodular categories, they say on page 14 that you can take a quotient of a premodular category $\mathcal{C}$ by its symmetric fusion subcategory …