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Various problems on integers lead to the class of congruence preserving functions on rings, i.e. functions verifying $a-b$ divides $f(a)-f(b)$ for all $a,b$. We characterized these classes of functions in terms of sums of rational…

Number Theory · Mathematics 2015-06-02 Patrick Cégielski , Serge Grigorieff , Irène Guessarian

We unravel a deep connection between limits of real numbers and limits in category theory. Using a new variant of the classical characterisation of the real numbers, we characterise the category of finite-dimensional Hilbert spaces and…

Category Theory · Mathematics 2025-11-18 Matthew Di Meglio , Chris Heunen

We propose a generalization of Quillen's exact category -- arithmetic exact category and we discuss conditions on such categories under which one can establish the notion of Harder-Narasimhan filtrations and Harder-Narsimhan polygons.…

Algebraic Geometry · Mathematics 2007-07-02 Huayi Chen

We introduce the notion of a definable category--a category equivalent to a full subcategory of a locally finitely presentable category that is closed under products, directed colimits and pure subobjects. Definable subcategories are…

Category Theory · Mathematics 2016-12-13 Amit Kuber , Jiří Rosický

We are checking the closed categories beginning with the category of sets and ending with the category of categories. The novelty is a generalizing the notion of adjoint functors to the joint pair of functors in the category of directed…

Category Theory · Mathematics 2022-09-22 Gintaras Valiukevičius

We study the structure of the category of representations of $\mathbf{FA}$, the category of finite sets and all maps, mostly working over a field of characteristic zero. This category is not semi-simple and exhibits interesting features. We…

Representation Theory · Mathematics 2025-09-16 Geoffrey Powell

In a locally $\lambda$-presentable category, with $\lambda$ a regular cardinal, classes of objects that are injective with respect to a family of morphisms whose domains and codomains are $\lambda$-presentable, are known to be characterized…

Category Theory · Mathematics 2020-12-04 Jiri Rosicky , Walter Tholen

Intra-class variations, distribution shifts among source and target domains are the major challenges of category-level tasks. In this study, we address category-level full 6D object pose estimation in the context of depth modality,…

Computer Vision and Pattern Recognition · Computer Science 2018-08-02 Caner Sahin , Tae-Kyun Kim

Simplicial presheaves on cartesian spaces provide a general notion of smooth spaces. There is a corresponding smooth version of the singular complex functor, which maps smooth spaces to simplicial sets. We consider the localisation of the…

Algebraic Topology · Mathematics 2022-11-16 Severin Bunk

Lenses are a well-established structure for modelling bidirectional transformations, such as the interactions between a database and a view of it. Lenses may be symmetric or asymmetric, and may be composed, forming the morphisms of a…

Machine Learning · Computer Science 2019-05-03 Brendan Fong , Michael Johnson

The paper uses the formalism of indexed categories to recover the proof of a standard final coalgebra theorem, thus showing existence of final coalgebras for a special class of functors on categories with finite limits and colimits. As an…

Logic · Mathematics 2007-05-23 Benno van den Berg , Federico De Marchi

One goal of applied category theory is to better understand networks appearing throughout science and engineering. Here we introduce "structured cospans" as a way to study networks with inputs and outputs. Given a functor $L \colon…

Category Theory · Mathematics 2020-11-11 John C. Baez , Kenny Courser

We present the first definition of strictly associative and unital $\infty$-category. Our proposal takes the form of a type theory whose terms describe the operations of such structures, and whose definitional equality relation enforces…

Category Theory · Mathematics 2024-07-08 Eric Finster , Alex Rice , Jamie Vicary

In this paper we propose and lay the foundations of a functorial framework for representing signals. By incorporating additional category-theoretic relative and generative perspective alongside the classic set-theoretic measure theory the…

Signal Processing · Electrical Eng. & Systems 2017-10-30 Salil Samant , Shiv Dutt Joshi

Neural network training is typically viewed as gradient descent on a loss surface. We propose a fundamentally different perspective: learning is a structure-preserving transformation (a functor L) between the space of network parameters…

Machine Learning · Computer Science 2025-10-07 Abdulrahman Tamim

Let $(\mathfrak{C},\mathbb{E},\mathfrak{s})$ be an Ext-finite, Krull-Schmidt and $k$-linear extriangulated category with $k$ a commutative artinian ring. We define an additive subcategory $\mathfrak{C}_r$ (respectively, $\mathfrak{C}_l$) of…

Representation Theory · Mathematics 2020-05-15 Tiwei Zhao , Lingling Tan , Zhaoyong Huang

A locally coherent exact category is a finitely accessible additive category endowed with an exact structure in which the admissible short exact sequences are the directed colimits of admissible short exact sequences of finitely presentable…

Category Theory · Mathematics 2024-07-31 Leonid Positselski

Category theory provides a means through which many far-ranging fields of mathematics can be related by their similar structure. In a paper by Robinson [2], this interconnectivity afforded by categorical perspectives allowed for the…

Algebraic Topology · Mathematics 2020-12-03 Karthik Boyareddygari

We study the category pro-SSet of pro-simplicial sets, which arises in etale homotopy theory, shape theory, and pro-finite completion. We establish a model structure on pro-SSet so that it is possible to do homotopy theory in this category.…

Algebraic Topology · Mathematics 2007-05-23 Daniel C. Isaksen

Given a tensor triangulated category we investigate the geometry of the Balmer spectrum as a locally ringed space. Specifically we construct functors assigning to every object in the category a corresponding sheaf and a notion of support…

Category Theory · Mathematics 2021-11-12 James Rowe