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We implement a novel representation of model search spaces as diagrams over a category of models, where we have restricted attention to a broad class of models whose structure is presented by \C-sets. (Co)limits in these diagram categories…

Logic in Computer Science · Computer Science 2022-06-20 Kristopher Brown , Tyler Hanks , James Fairbanks

A semisimple algebraic tensor category over an algebraically closed field k of characteristic zero is the representation category of all finite dimensional twisted super representations of an affine reductive supergroup G over k. Such a…

Category Theory · Mathematics 2009-09-10 Rainer Weissauer

We define the notion of accessibility for a pro-$p$ group. We prove that finitely generated pro-$p$ groups are accessible given a bound on the size of their finite subgroups. We then construct a finitely generated inaccessible pro-$p$…

Group Theory · Mathematics 2018-11-07 Gareth Wilkes

The so-called algebraic approach to the constraint satisfaction problem (CSP) has been a prevalent method of the study of complexity of these problems since early 2000's. The core of this approach is the notion of polymorphisms which…

Logic in Computer Science · Computer Science 2026-05-15 Maximilian Hadek , Tomáš Jakl , Jakub Opršal

The category of admissible (in the appropriately modified sense of representation theory of totally disconnected groups) semi-linear representations of the automorphism group of an algebraically closed extension of infinite transcendence…

Representation Theory · Mathematics 2009-04-07 M. Rovinsky

We introduce the notion of a $c$-category, which is a kind of category whose behaviour is controlled by connective ring spectra. More precisely, any $c$-category admits a finite step resolution by categories of compact modules over…

K-Theory and Homology · Mathematics 2025-09-19 Ishan Levy , Vladimir Sosnilo

We establish a general method to produce cofibrant approximations in the model category $U_S(C,D)$ of $S$-valued $C$-indexed diagrams with $D$-weak equivalences and $D$-fibrations. We also present explicit examples of such approximations.…

K-Theory and Homology · Mathematics 2007-05-23 Paul Balmer , Michel Matthey

We discover a large class of simple affine vertex algebras $V_{k} (\mathfrak g)$, associated to basic Lie superalgebras $\mathfrak g$ at non-admissible collapsing levels $k$, having exactly one irreducible $\mathfrak g$-locally finite…

Representation Theory · Mathematics 2024-12-03 Drazen Adamovic , Victor G. Kac , Pierluigi Moseneder Frajria , Paolo Papi , Ozren Perse

Let G be a connected simple adjoint p-adic group not isomorphic to a projective linear group PGL(m,D) of a division algebra D, or an adjoint ramified unitary group of a split hermitian form in 3 variables. We prove that G admits an…

Number Theory · Mathematics 2018-01-01 Marie-France Vignéras

A QSIN group is a locally compact group $G$ whose group algebra $L^1(G)$ admits a quasi-central bounded approximate identity. Examples of QSIN groups include every amenable group and every discrete group. It is shown that if $G$ is a QSIN…

Operator Algebras · Mathematics 2017-05-19 Matthew Wiersma

We extend the Kechris--Pestov--Todor\v{c}evi\'c correspondence to weak Fra\"{\i}ss\'{e} categories and automorphism groups of generic objects. The new ingredient is the weak Ramsey property. We demonstrate the theory on several examples…

Logic · Mathematics 2024-11-20 Adam Bartoš , Tristan Bice , Keegan Dasilva Barbosa , Wiesław Kubiś

Restriction categories provide a categorical framework for partiality. In this paper, we introduce three new categorical theories for partiality: local categories, partial categories, and inclusion categories. The objects of a local…

Category Theory · Mathematics 2025-12-04 Marcello Lanfranchi , Jean-Simon Pacaud Lemay

We introduce a notion of partial presentability in parametrized higher category theory and investigate its interaction with the concepts of parametrized semiadditivity and stability from arXiv:2301.08240. In particular, we construct the…

Algebraic Topology · Mathematics 2025-09-19 Bastiaan Cnossen , Tobias Lenz , Sil Linskens

We study a new type of higher categorical structure, called weakly globular n-fold category, previously introduced by the author. We show that this structure is a model of weak n-categories by proving that it is suitably equivalent to the…

Category Theory · Mathematics 2016-09-15 Simona Paoli

We relativise the Thomassen--Woess definition of accessibility in graphs, defining what it means for a graph to be accessible relative to a peripheral system. In the case of locally finite, quasi-transitive graphs, we characterise relative…

Combinatorics · Mathematics 2026-05-14 Joseph Paul MacManus

A topological group is (openly) almost-elliptic if it contains a(n open) dense subset of elements generating relatively-compact cyclic subgroups. We classify the (openly) almost-elliptic connected locally compact groups as precisely those…

Group Theory · Mathematics 2025-06-12 Alexandru Chirvasitu

A group-category is an additively semisimple category with a monoidal product structure in which the simple objects are invertible. For example in the category of representations of a group, 1-dimensional representations are the invertible…

Geometric Topology · Mathematics 2007-05-23 Frank Quinn

In this paper we prove that various quasi-categories whose objects are $\infty$-categories in a very general sense are complete: admitting limits indexed by all simplicial sets. This result and others of a similar flavor follow from a…

Category Theory · Mathematics 2019-10-04 Emily Riehl , Dominic Verity

Let $G$ be a real reductive Lie group, $L$ a compact subgroup, and $\pi$ an irreducible admissible representation of $G$. In this article we prove a necessary and sufficient condition for the finiteness of the multiplicities of $L$-types…

Representation Theory · Mathematics 2023-04-25 Toshiyuki Kobayashi

We propose a generalization of Categorial Grammar in which lexical categories are defined by means of recursive constraints. In particular, the introduction of relational constraints allows one to capture the effects of (recursive) lexical…

cmp-lg · Computer Science 2008-02-03 Gosse Bouma , Gertjan van Noord
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