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We provide a new description of the hom functor on weak $\omega$-categories, and we show that it admits a left adjoint that we call the suspension functor. We then show that the hom functor preserves the property of being free on a…

Category Theory · Mathematics 2024-11-14 Thibaut Benjamin , Ioannis Markakis

This article gives an elementary and formal 2-categorical construction of a bicategory of right fractions analogous to anafunctors, starting from a 2-category equipped with a family of covering maps that are fully faithful and co-fully…

Category Theory · Mathematics 2021-09-24 David Michael Roberts

We record an explicit proof of the theorem that lifts a two-variable adjunction to the arrow categories of its domains.

Category Theory · Mathematics 2019-02-19 Fosco Loregian

We study selfadjoint functors acting on categories of finite dimensional modules over finite dimensional algebras with an emphasis on functors satisfying some polynomial relations. Selfadjoint functors satisfying several easy relations, in…

Representation Theory · Mathematics 2011-09-08 Troels Agerholm , Volodymyr Mazorchuk

This article is an introduction to the basic generalized category theory used in recent work on an extension of the theory of categories and categorical logic, including parts of topos theory. We discuss functors, equivalences, natural…

Category Theory · Mathematics 2017-12-27 Lucius T. Schoenbaum

Suppose that $F: \mathcal{N} \to \mathcal{M}$ is a functor whose target is a Quillen model category. We give a succinct sufficient condition for the existence of the right-induced model category structure on $\mathcal{N}$ in the case when…

Category Theory · Mathematics 2026-03-13 Gabriel C. Drummond-Cole , Philip Hackney

Expansions of abelian categories are introduced. These are certain functors between abelian categories and provide a tool for induction/reduction arguments. Expansions arise naturally in the study of coherent sheaves on weighted projective…

Representation Theory · Mathematics 2010-09-20 Xiao-Wu Chen , Henning Krause

This paper describes several cases of adjunction in the homomorphism preorder of relational structures. We say that two functors $\Lambda$ and $\Gamma$ between thin categories of relational structures are adjoint if for all structures…

Combinatorics · Mathematics 2024-04-10 Víctor Dalmau , Andrei Krokhin , Jakub Opršal

In the category of monoids we characterize monomorphisms that are normal, in an appropriate sense, to internal reflexive relations, preorders or equivalence relations. The zero-classes of such internal relations are first described in terms…

Category Theory · Mathematics 2022-10-10 Nelson Martins-Ferreira , Manuela Sobral

We construct a functor from the category of graphs to the category of groups which is faithful and "almost" full, in the sense that it induces bijections of the Hom sets up to trivial homomorphisms and conjugation in the category of groups.…

Group Theory · Mathematics 2010-05-19 Adam J. Przezdziecki

We investigate fundamental properties of adjoint functors to the precomposition functor in the category of strict polynomial functors.

K-Theory and Homology · Mathematics 2014-11-11 Marcin Chałupnik

Each distributor between categories enriched over a small quantaloid Q gives rise to two adjunctions between the categories of contravariant and covariant presheaves, and hence to two monads. These two adjunctions are respectively…

Category Theory · Mathematics 2013-07-23 Lili Shen , Dexue Zhang

We construct a left semi-model structure on the category of intensional type theories (precisely, on $\mathrm{CxlCat_{Id,1,\Sigma(,\Pi_{ext})}}$). This presents an $\infty$-category of such type theories; we show moreover that there is an…

Category Theory · Mathematics 2026-02-06 Chris Kapulkin , Peter LeFanu Lumsdaine

We construct an adjunction between $m$-categories internal to $(\infty,n)$-categories, called $(n,m)$-double $\infty$-categories, and filtrations $A_0\to \dots\to A_m$ where for all $i<m$, $A_i$ is a $(n+i)$-category. We show that this…

Category Theory · Mathematics 2025-03-26 Félix Loubaton

The notion of a duality between two derived functors as well as an extension theorem for derived functors to larger categories in which they need not be defined is introduced. These ideas are then applied to extend and study the coext…

Rings and Algebras · Mathematics 2014-02-19 Anastasis Kratsios

The purpose of this article is threefold: Firstly, we propose some enhancements to the existing definition of 6-functor formalisms. Secondly, we systematically study the category of kernels, which is a certain 2-category attached to every…

Category Theory · Mathematics 2024-10-18 Claudius Heyer , Lucas Mann

This note presents the classification of ladder operators corresponding to the class of rational extensions of the harmonic oscillator. We show that it is natural to endow the class of rational extensions and the corresponding intertwining…

Mathematical Physics · Physics 2019-10-29 David Gomez-Ullate , Yves Grandati , Zoe McIntyre , Robert Milson

Adjunctions of two variables generalize the relationship between tensor product and the internal hom functor in a closed monoidal category. For a pair of ordinary adjunctions $(F\dashv U, F'\dashv U')$ conjugation relates natural…

Category Theory · Mathematics 2025-01-06 Simon Willerton

We define extension $\infty$-categories for exact $\infty$-categories in terms of bifibrations. Extension $\infty$-categories are invariant when passing to the stable hull, and consequently we show that they form an $\Omega$-spectrum,…

Category Theory · Mathematics 2023-08-29 Erlend D. Børve , Paul Trygsland

Given a diagram of small categories $F : J \rightarrow \textbf{Cat}$, we provide a combinatorial description of its colimit in terms of the indexing category $J$ and the categories and functors in the diagram $F$. We introduce certain…

Category Theory · Mathematics 2023-09-19 Redi Haderi