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Given a finite dimensional algebra $\Lambda$, we show that a frequently satisfied finiteness condition for the category ${\cal P}^{\infty}(\Lambda\rm{-mod})$ of all finitely generated (left) $\Lambda$-modules of finite projective dimension,…

Representation Theory · Mathematics 2014-07-10 B. Huisgen-Zimmermann , S. O. Smalø

The injective right comodules appearing in the minimal injective resolution of a finite-dimensional comodule need not to be of finite dimension or even quasi-finite. The obstruction here is that factor comodules of quasi-finite comodules…

Rings and Algebras · Mathematics 2007-05-23 J. Gomez-Torrecillas , C. Nastasescu , B. Torrecillas

We introduce the notion of $\lambda$-equivalence and $\lambda$-embeddings of objects in suitable categories. This notion specializes to $L_{\infty\lambda}$-equivalence and $L_{\infty\lambda}$-elementary embedding for categories of…

Category Theory · Mathematics 2020-12-04 Tibor Beke , Jiri Rosicky

Arboreal categories provide an axiomatic framework in which abstract notions of bisimilarity and back-and-forth games can be defined. They act on extensional categories, typically consisting of relational structures, via arboreal…

Logic in Computer Science · Computer Science 2025-02-05 Luca Reggio , Colin Riba

We extend the 2-representation theory of finitary 2-categories to certain 2-categories with infinitely many objects, denoted locally finitary 2-categories, and extend the classical classification results of simple transitive…

Category Theory · Mathematics 2022-01-19 James Macpherson

We recall the notions of a graded cocategory, conilpotent cocategory, morphisms of such (cofunctors), coderivations and define their analogs in $\mathbb L$-filtered setting. The difference with the existing approaches: we do not impose any…

Category Theory · Mathematics 2020-10-13 Volodymyr Lyubashenko

We define the notion of a $\lambda$-definable category, a generalisation of the notion of definable category from the model theory of modules. Let ${\cal C}$ be a $\lambda$-accessible additive category. We characterise the additive functors…

Representation Theory · Mathematics 2025-01-08 Samuel Dean

We present a finitary version of Moss' coalgebraic logic for $T$-coalgebras, where $T$ is a locally monotone endofunctor of the category of posets and monotone maps. The logic uses a single cover modality whose arity is given by the least…

Logic in Computer Science · Computer Science 2023-06-22 Marta Bílková , Matěj Dostál

Self-similar groups provide a rich source of groups with interesting properties; e.g., infinite torsion groups (Burnside groups) and groups with an intermediate word growth. Various self-similar groups can be described by a recursive…

Group Theory · Mathematics 2012-04-20 René Hartung

It has been conjectured that finite tensor categories have finitely generated cohomology. We show that this is equivalent to finitely generated Hochschild cohomology for the endomorphism algebras of the projective generators.

Quantum Algebra · Mathematics 2026-04-23 Petter Andreas Bergh

Using the theory of coalgebra, we introduce a uniform framework for adding modalities to the language of propositional geometric logic. Models for this logic are based on coalgebras for an endofunctor on some full subcategory of the…

Logic · Mathematics 2023-06-22 Nick Bezhanishvili , Jim de Groot , Yde Venema

In this survey, we first present basic facts on A-infinity algebras and modules including their use in describing triangulated categories. Then we describe the Quillen model approach to A-infinity structures following K. Lefevre's thesis.…

Representation Theory · Mathematics 2007-05-23 Bernhard Keller

In this contribution, we aim to introduce and study L-fuzzy partition spaces and L-fuzzy closure system spaces in a categorical framework. Further, we present the concepts of coalgebras and dialgebras corresponding to a direct upper F…

Category Theory · Mathematics 2022-12-19 Abha Tripathi , S. P. Tiwari

We give an explicit description of the generator of finitely presented objects of the coslice of a locally finitely presentable category under a given object, as consisting of all pushouts of finitely presented maps under this object. Then…

Category Theory · Mathematics 2021-04-15 Axel Osmond

For a recollement $(\mathcal{D}B,\mathcal{D}A,\mathcal{D}C)$ of derived categories of algebras, we investigate when the functor $j^*:\mathcal{D}A\rightarrow\mathcal{D}C$ is an eventually homological isomorphism. In this context, we compare…

Representation Theory · Mathematics 2018-07-03 Yongyun Qin

Automatic presentations, also called FA-presentations, were introduced to extend finite model theory to infinite structures whilst retaining the solubility of fundamental decision problems. This paper studies FA-presentable algebras. First,…

Logic · Mathematics 2015-10-21 Alan J. Cain , Nik Ruškuc

This paper studies fundamental questions concerning category-theoretic models of induction and recursion. We are concerned with the relationship between well-founded and recursive coalgebras for an endofunctor. For monomorphism preserving…

Logic in Computer Science · Computer Science 2020-02-18 Jiří Adámek , Stefan Milius , Lawrence S. Moss

An algebra is said to be \emph{$\tau$-tilting finite} provided it has only a finite number of $\tau$-rigid objects up to isomorphism. We associate a category to each such algebra. The objects are the wide subcategories of its category of…

Representation Theory · Mathematics 2020-12-21 Aslak Bakke Buan , Bethany Marsh

We consider two endofunctors of the form $~F:X\longrightarrow M\otimes X~$, where $~M~$ is a non degenerate module, related to the unit interval and the Sierpinski gasket, and their final co-algebras. The functors are defined on the…

Category Theory · Mathematics 2017-10-23 Annanthakrishna Manokaran , Romaine Jayewardene , Jayampathy Ratnayake

Kurz et al. have recently shown that infinite $\lambda$-trees with finitely many free variables modulo $\alpha$-equivalence form a final coalgebra for a functor on the category of nominal sets. Here we investigate the rational fixpoint of…

Category Theory · Mathematics 2015-06-01 Stefan Milius , Thorsten Wißmann