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The work is devoted to the extension groups in the category of functors from a small category to an additive category with an Abelian structure in the sense of Heller. It is constructed a spectral sequence which converges to the extension…

Category Theory · Mathematics 2009-09-28 A. A. Husainov , A. Pancar , M. Yapici

Cartesian fibrations were originally defined by Lurie in the context of quasi-categories and are commonly used in $(\infty,1)$-category theory to study presheaves valued in $(\infty,1)$-categories. In this work we define and study…

Category Theory · Mathematics 2021-02-12 Nima Rasekh

In [1] we introduced the concept of structured space, which is a topological space that locally resembles some algebraic structures. In [2] we proceeded the study of these spaces, developing two cohomology theories. The aim of this paper is…

Algebraic Topology · Mathematics 2020-04-28 Manuel Norman

We introduce the notion of quasi-Ehresmann-Dedecker universes in quasi-set theory in order to get a framework to develop a categorical version of quasi-set theory, so characterizing the category Qset in a similar way as the category Set is…

Logic · Mathematics 2017-08-22 Decio Krause

Recent work in set theory indicates that there are many different notions of 'set', each captured by a different collection of axioms, as proposed by J. Hamkins in [Ham11]. In this paper we strive to give one class theory that allows for a…

Logic · Mathematics 2022-06-10 Alec Rhea

In [1] we defined a new kind of space called 'structured space' which locally resembles, near each of its points, some algebraic structure. We noted in the conclusion of the cited paper that the maps $f_s$ and $h$, which are of great…

Algebraic Topology · Mathematics 2020-04-27 Manuel Norman

We prove a single category-theoretic result encapsulating the notions of ultrafilters, ultrapower, ultraproduct, tensor product of ultrafilters, the Rudin--Kiesler partial ordering on ultrafilters, and Blass's category of ultrafilters UF.…

Category Theory · Mathematics 2020-06-03 Richard Garner

Given a category $\mathcal C$ and a directed partially ordered set $J$, a certain category $pro^J -\mathcal C$ on inverse systems in $\mathcal C$ is constructed such that the ordinary pro-category $pro-\mathcal C$ is the most special case…

Category Theory · Mathematics 2019-05-20 Nikica Uglešić

An important goal in studying the relations between unitary VOAs and conformal nets is to prove the equivalence of their ribbon categories. In this article, we prove this conjecture for many familiar examples. Our main idea is to construct…

Quantum Algebra · Mathematics 2021-04-06 Bin Gui

Nearly Frobenius structures and 2-dimensional Almost TQFTs were introduced and shown to be in categorical equivalence in arXiv:1907.05470 in the attempt to extend the Atiyah-Segal's definition to the category of infinite dimensional vector…

Algebraic Geometry · Mathematics 2025-11-14 William Davis , Olivia Dumitrescu

We construct a one-parameter family of Lorentzian conformal structures on the canonical circle bundle of a partially integrable contact almost Cauchy-Riemann manifold. This builds on previous work by Leitner, who generalised Fefferman's…

Differential Geometry · Mathematics 2025-06-11 Arman Taghavi-Chabert

This paper introduces almost partitionable sets to generalize the known concept of partitionable sets. These notions provide a unified frame to construct $\mathbb{Z}$-cyclic patterned starter whist tournaments and cyclic balanced sampling…

Combinatorics · Mathematics 2023-11-27 Yanxun Chang , Simone Costa , Tao Feng , Xiaomiao Wang

Let $(\mathcal{C},\mathbb{E},\mathfrak{s})$ be an extriangulated category with a proper class $\xi$ of $\mathbb{E}$-triangles. In this paper, we study the quasi-Gorensteinness of extriangulated categories. More precisely, we introduce the…

Representation Theory · Mathematics 2025-01-14 Zhenggang He

We develop a representation theory of categories as a means to explore characteristic structures in algebra. Characteristic structures play a critical role in isomorphism testing of groups and algebras, and their construction and…

Group Theory · Mathematics 2025-11-20 Peter A. Brooksbank , Heiko Dietrich , Joshua Maglione , E. A. O'Brien , James B. Wilson

We introduce a notion of (co)presheaf on a lax double functor $X$, which we generally call an instance. In the terminology of double-categorical logic, a lax double functor valued in sets, possibly preserving finite products, is called a…

Category Theory · Mathematics 2026-05-06 Kevin Carlson , Evan Patterson

We use the terms $\infty$-categories and $\infty$-functors to mean the objects and morphisms in an $\infty$-cosmos: a simplicially enriched category satisfying a few axioms, reminiscent of an enriched category of fibrant objects.…

Category Theory · Mathematics 2016-06-14 Emily Riehl , Dominic Verity

This is the third in a series of papers extending Martin-L\"of's meaning explanations of dependent type theory to a Cartesian cubical realizability framework that accounts for higher-dimensional types. We extend this framework to include a…

Logic in Computer Science · Computer Science 2017-12-06 Carlo Angiuli , Kuen-Bang Hou , Robert Harper

We give a presentation of Feynman categories from a representation--theoretical viewpoint. Feynman categories are a special type of monoidal categories and their representations are monoidal functors. They can be viewed as a far reaching…

Representation Theory · Mathematics 2020-10-27 Ralph M. Kaufmann

This is the first of a series of papers on enriched infinity categories, seeking to reduce enriched higher category theory to the higher algebra of presentable infinity categories, which is better understood and can be approached via…

Category Theory · Mathematics 2020-08-27 John D. Berman

Partial descriptions of the Universe are presented in the form of linear equations considered in the free (full, super) Fock space. The universal properties of these equations are discussed. The closure problem caused by computational and…

General Physics · Physics 2010-10-19 Jerzy Hanckowiak