English

Symmetric tensor categories in characteristic 2

Representation Theory 2020-05-29 v4

Abstract

We construct and study a nested sequence of finite symmetric tensor categories Vec=C0C1Cn{\rm Vec}=\mathcal{C}_0\subset \mathcal{C}_1\subset\cdots\subset \mathcal{C}_n\subset\cdots over a field of characteristic 22 such that C2n\mathcal{C}_{2n} are incompressible, i.e., do not admit tensor functors into tensor categories of smaller Frobenius--Perron dimension. This generalizes the category C1\mathcal{C}_1 described by Venkatesh and the category C2\mathcal{C}_2 defined by Ostrik. The Grothendieck rings of the categories C2n\mathcal{C}_{2n} and C2n+1\mathcal{C}_{2n+1} are both isomorphic to the ring of real cyclotomic integers defined by a primitive 2n+22^{n+2}-th root of unity, On=Z[2cos(π/2n+1)]\mathcal{O}_n=\mathbb Z[2\cos(\pi/2^{n+1})].

Keywords

Cite

@article{arxiv.1807.05549,
  title  = {Symmetric tensor categories in characteristic 2},
  author = {Dave Benson and Pavel Etingof},
  journal= {arXiv preprint arXiv:1807.05549},
  year   = {2020}
}

Comments

27 pages, latex; in v2 corrections made suggested by the referee and a number of results added, in particular Corollary 2.5 and Proposition 2.6; introduction expanded; in v.4 small errors in Propositions 3.3, 3.4, Corollary 3.5, and Propositions 3.9, 3.16 (proofs) fixed, and the reference to [CEH] added

R2 v1 2026-06-23T03:01:50.343Z