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Lucatelli Nunes obtained a 2-categorical version of the adjoint triangle theorem of Dubuc using the descent object of a specific diagram. In some cases, such a diagram can be filled with an extra cell. We show then how to obtain a biadjoint…

Category Theory · Mathematics 2025-03-14 Gabriel Merlin

We prove that there is an adjunction between what we call \'etale topological categories and restriction quantal frames that leads to an adjunction with a category of complete restriction monoids. This generalizes the adjunction between…

Category Theory · Mathematics 2023-03-10 Mark V. Lawson

There is some consensus among orthodox category theorists that the concept of adjoint functors is the most important concept contributed to mathematics by category theory. We give a heterodox treatment of adjoints using heteromorphisms…

Category Theory · Mathematics 2015-08-18 David Ellerman

We study lax functors between bicategories as a generalized concept of monads and describe generalized notions and theorems of formal monad theory for lax functors. Our first approach is to use the 2-monad whose lax algebras are lax…

Category Theory · Mathematics 2024-09-20 Kengo Hirata

We study right quasi-representable differential graded bimodules as quasi-functors between dg-categories. We prove that a quasi-functor has a left adjoint if and only if it is left quasi-representable.

Category Theory · Mathematics 2015-10-19 Francesco Genovese

In this paper is presented a new approach to the axiomatic homotopy theory in categories, which offers a simpler and more useful answer to this old question: how two objects in a category (without any topological feature) can be deformed…

Category Theory · Mathematics 2007-05-23 Adrian Duma , Cristian Vladmirescu

The functor that takes a ring to its category of modules has an adjoint if one remembers the forgetful functor to abelian groups: the endomorphism ring of linear natural transformations. This uses the self-enrichment of the category of…

Category Theory · Mathematics 2020-03-09 Gabriel C. Drummond-Cole , Joseph Hirsh , Damien Lejay

We give a semantics for the lambda-calculus based on a topological duality theorem in nominal sets. A novel interpretation of lambda is given in terms of adjoints, and lambda-terms are interpreted absolutely as sets (no valuation is…

Logic in Computer Science · Computer Science 2016-10-07 Murdoch J. Gabbay , Michael J. Gabbay

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

Quasi-set theory is a first order theory without identity, which allows us to cope with non-individuals in a sense. A weaker equivalence relation called ``indistinguishability'' is an extension of identity in the sense that if $x$ is…

Quantum Physics · Physics 2015-06-26 Adonai S. Sant'Anna

Like categories, small 2-categories have well-understood classifying spaces. In this paper, we deal with homotopy types represented by 2-diagrams of 2-categories. Our results extend to homotopy colimits of 2-functors lower categorical…

Category Theory · Mathematics 2015-04-24 A. M. Cegarra , B. A. Heredia

We develop the theory of strong and commutative monads in the 2-dimensional setting of bicategories. This provides a framework for the analysis of effects in many recent models which form bicategories and not categories, such as those based…

Logic in Computer Science · Computer Science 2024-06-12 Hugo Paquet , Philip Saville

We want to replace categories, functors and natural transformations by categories, open functors and open natural transformations. In analogy with open dynamical systems, the adjective open is added here to mean that some external…

Category Theory · Mathematics 2021-02-17 Alexandre Fernandez , Luidnel Maignan , Antoine Spicher

A skeleton of the category with finite coproducts D freely generated by a single object has a subcategory isomorphic to a skeleton of the category with finite products C freely generated by a countable set of objects. As a consequence, we…

Logic · Mathematics 2016-06-10 Kosta Dosen , Zoran Petric

We define the notion of an indexed profunctor over a 2-category, and use it to develop an abstract theory of limits. The theory subsumes (conical) limits, weighted limits, ends and Kan extensions. Results include an abstract version of the…

Category Theory · Mathematics 2023-02-14 Sori Lee

We provide two alternative ways to determine the number of (bi-)twisted conjugacy classes in a finite group: one by counting certain irreducible characters and one by counting certain twisted conjugacy classes of other endomorphisms. In…

Group Theory · Mathematics 2026-03-03 Pieter Senden , Sam Tertooy

We give a systematic construction of epimorphisms between 2-bridge link groups. Moreover, we show that 2-bridge links having such an epimorphism between their link groups are related by a map between the ambient spaces which only have a…

Geometric Topology · Mathematics 2009-04-14 Tomotada Ohtsuki , Robert Riley , Makoto Sakuma

We study two modifications of the Post Correspondence Problem (PCP), namely 1) the bi-infinite version, where it is asked whether there exists a bi-infinite word such that two given morphisms agree on it, and 2) the conjugate version, where…

Discrete Mathematics · Computer Science 2022-09-16 Olivier Finkel , Vesa Halava , Tero Harju , Esa Sahla

Categorical structures and their pseudomaps rarely form locally presentable 2-categories in the sense of Cat-enriched category theory. However, we show that if the categorical structure in question is sufficiently weak (such as the…

Category Theory · Mathematics 2022-01-31 John Bourke

This paper is concerned with the characterizations of quasi self-adjoint extensions of a class of formally non-self-adjoint discrete Hamiltonian systems. Some properties of the solutions and the characterization of the minimal linear…

Spectral Theory · Mathematics 2025-12-11 Guojing Ren , Guixin Xu