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Topological quantum field theory.

23 votes
5 answers
3k views

Do all 3D TQFTs come from Reshetikhin-Turaev?

The Reshetikhin-Turaev construction take as input a Modular Tensor Category (MTC) and spits out a 3D TQFT. I've been told that the other main construction of 3D TQFTs, the Turaev-Viro State sum constr …
Chris Schommer-Pries's user avatar
17 votes
Accepted

How aggressive is the fibrant replacement of $\mathrm{Bord}_n$?

The completeness condition is not really about making things invertible which weren't already. It is about where the information about invertible morphisms is stored. We can already see this with $(\i …
Chris Schommer-Pries's user avatar
15 votes
Accepted

Cohomology rings and 2D TQFTs

These 2D TQFTs do not come from extended theories (unless X is discrete). I interpret this as saying that these theories are non-local (in the 2D bordism) and so you will have trouble interpreting the …
Chris Schommer-Pries's user avatar
15 votes

What's the right way to think about "anomalies" in 3d TQFTs?

There are several different kinds of TQFTs that can be defined. For example there are oriented theories, unoriented theories, framed theories, and many more. The 3D TQFTs coming from Modular Tensor Ca …
Chris Schommer-Pries's user avatar
13 votes
1 answer
308 views

Does the Turaev-Viro theory for the generalized $E_6$ subfactor for $\mathbb{Z}/7$ distingui...

In the paper Sato-Wakui "COMPUTATIONS OF TURAEV-VIRO-OCNEANU INVARIANTS OF 3-MANIFOLDS FROM SUBFACTORS" they compute certain Turaev-Viro-Ocneanu invariants of certain lens spaces. One of the results i …
Chris Schommer-Pries's user avatar
13 votes

Why are fusion categories interesting?

I also wrote a sequence of blog posts explaining the Turaev-Viro construction from the point of view of planar algebras. It has pretty pictures and might be relevant. TQFTs via Planar Algebras I TQF …
12 votes
Accepted

How unique are extensions of TQFTs to lower dimension?

The question of which tqfts extend is a very interesting one. To make the question more mathematically precise, we can fix the target n-categories and ask for the tqfts to extend with respect to those …
Chris Schommer-Pries's user avatar
11 votes
1 answer
230 views

Are algebras with invertible linear duals always Frobenius?

Let $A$ be a finite dimensional algebra over a ground field $k$. The linear dual $A^* = Hom_k(A,k)$ is naturally an $A$-$A$ bimodule. I am interested in those algebras such that $A^*$ is an invertible …
Chris Schommer-Pries's user avatar
11 votes
0 answers
412 views

When can we tell if PROPs, Algebraic Theories, etc. are faithfully detected in a given categ...

I am interested in understanding a certain phenomenon. I am hoping this sort of problem has been studied before, but I don't know the proper terminology and am having trouble finding answers. I am goi …
Chris Schommer-Pries's user avatar
10 votes
Accepted

Homotopy Fixed Points of SO(2) on Fully Dualizable Algebras

I might be confused about your question. Are you asking... How is trivializing the $O(n)$-action the same as giving an $O(n)$-equivariant non-degenerate trace? (as per Lurie's theorem 3.1.8). How ca …
Chris Schommer-Pries's user avatar
10 votes
2 answers
1k views

Segal's 1999 Stanford lecture notes on TQFT, where to find them?

I am trying to track down a copy of Graeme Segal's 1999 lecture notes on topological field theory. These are sometimes referred to as the "Stanford lectures" or something similar. For many years the …
Chris Schommer-Pries's user avatar
9 votes
Accepted

Spin TQFT's in dimensions (1+1)

This is covered in Moore and Segal "D-branes and K-theory in 2D topological field theory". In particular on around page 16 there is a characterization analogous to "1+1 TQFTs = Commutative Frobenius a …
Chris Schommer-Pries's user avatar
9 votes
Accepted

Are there examples of finite-dimensional complex non-semisimple non-commutative symmetric Fr...

Given any finite dimensional algebra $A$, consider the linear dual $\hat{A}= \hom(A, k)$ as an $A$-$A$-bimodule. Then $R = A \oplus \hat{A}$ may be equipped with an algebra structure as follows: $$(a, …
Chris Schommer-Pries's user avatar
8 votes
1 answer
446 views

Separable and finitely generated projective but not Frobenius?

Let R be a commutative ring, and $A$ an $R$-algebra (possibly non-commutative). Then $A$ is separable if it is finitely generated (f.g.) projective as an $(A \otimes_R A^{\mathrm{op}})$-algebra. Suppo …
Chris Schommer-Pries's user avatar
7 votes
Accepted

Are there 4d state sum models, extended TQFTs or chain mail invariant that detect smooth str...

This MO answer by Arun Debray gives an example in the unoriented case where two specific homeomorphic manifolds can be distinguished by a specific TFT of this kind. In general all these constructions …
Chris Schommer-Pries's user avatar

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