English

Extracting an $\mathbb{N}$-filtered differential modality from a differential modality

Category Theory 2026-04-20 v1 Logic in Computer Science

Abstract

A differential modality is a comonad on an additive symmetric monoidal category (C,,I)(\mathsf{C},\otimes,I), whose underlying functor we denote ! ⁣:CC!\colon\mathsf{C} \rightarrow \mathsf{C}, together with some additional structure including a differential operator  ⁣:!AA!A\partial\colon!A \otimes A \rightarrow !A. A morphism f ⁣:!ABf\colon !A \rightarrow B is interpreted as a smooth function from AA to BB. The notion of an N\mathbb{N}-filtered differential modality is a variant in which a notion of degree is present. Instead of a single functor ! ⁣:CC!\colon \mathsf{C} \rightarrow \mathsf{C}, we ask for a family of functors !n ⁣:CC!_{\le n}\colon\mathsf{C} \rightarrow \mathsf{C} where nNn \in \mathbb{N}. Now, a morphism f ⁣:!nABf\colon !_{\le n} A \rightarrow B is interpreted as a smooth function from AA to BB, with degree less than nn for some notion of degree. We prove that under mild conditions, every differential modality on an additive symmetric monoidal category with underlying functor ! ⁣:CC!\colon \mathsf{C} \rightarrow \mathsf{C} yields an N\mathbb{N}-filtered differential modality with underlying functors !n ⁣:CC!_{\le n}\colon\mathsf{C} \rightarrow \mathsf{C}. A morphism f ⁣:!nABf\colon !_{\le n}A \rightarrow B corresponds to a polynomial map of degree less than nn from AA to BB, in the sense that the (n+1)(n+1)-th derivative of ff is 00.

Keywords

Cite

@article{arxiv.2604.16016,
  title  = {Extracting an $\mathbb{N}$-filtered differential modality from a differential modality},
  author = {Jean-Baptiste Vienney},
  journal= {arXiv preprint arXiv:2604.16016},
  year   = {2026}
}

Comments

51 pages

R2 v1 2026-07-01T12:14:20.796Z