English

Polynomial functors on some categories of elements

Category Theory 2023-11-22 v2

Abstract

We study the category F(SS,V)\mathcal{F}(\mathfrak{S}_S,\mathcal{V}) of functors from the category SS\mathfrak{S}_S, which is the category of elements of some presheaf SS on the category Vf\mathcal{V}^f of finite dimensional vector spaces, to V\mathcal{V} the category of vector spaces of any dimension on some field k\mathbb{k}. In the case where SS satisfies some noetherianity condition, we have a convenient description of the category SS\mathfrak{S}_S. In this case, we can define a notion of polynomial functors on SS\mathfrak{S}_S. And, like in the usual setting of functors from the category of finite dimensional vector spaces to the one of vector spaces of any dimension, we can describe the quotient Poln(SS,V)/Poln1(SS,V)\mathcal{P}\mathrm{ol}_{n}(\mathfrak{S}_S,\mathcal{V})/\mathcal{P}\mathrm{ol}_{n-1}(\mathfrak{S}_S,\mathcal{V}), where Poln(SS,V)\mathcal{P}\mathrm{ol}_{n}(\mathfrak{S}_S,\mathcal{V}) denote the full subcategory of F(SS,V)\mathcal{F}(\mathfrak{S}_S,\mathcal{V}) of polynomial functors of degree less than or equal to nn. Finally, if k=Fp\mathbb{k}=\mathbb{F}_p for some prime pp and if SS satisfies the required noetherianity condition, we can compute the set of isomorphism classes of simple objects in F(SS,V)\mathcal{F}(\mathfrak{S}_S,\mathcal{V}).

Keywords

Cite

@article{arxiv.2310.00186,
  title  = {Polynomial functors on some categories of elements},
  author = {Ouriel Bloede},
  journal= {arXiv preprint arXiv:2310.00186},
  year   = {2023}
}

Comments

14 pages

R2 v1 2026-06-28T12:36:48.937Z