Arboreal Categories: An Axiomatic Theory of Resources

Game comonads provide a categorical syntax-free approach to finite model theory, and their Eilenberg-Moore coalgebras typically encode important combinatorial parameters of structures. In this paper, we develop a framework whereby the essential properties of these categories of coalgebras are captur...

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Main Authors: Samson Abramsky, Luca Reggio
Format: Article
Language:English
Published: Logical Methods in Computer Science e.V. 2023-08-01
Series:Logical Methods in Computer Science
Subjects:
Online Access:https://lmcs.episciences.org/9839/pdf
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author Samson Abramsky
Luca Reggio
author_facet Samson Abramsky
Luca Reggio
author_sort Samson Abramsky
collection DOAJ
description Game comonads provide a categorical syntax-free approach to finite model theory, and their Eilenberg-Moore coalgebras typically encode important combinatorial parameters of structures. In this paper, we develop a framework whereby the essential properties of these categories of coalgebras are captured in a purely axiomatic fashion. To this end, we introduce arboreal categories, which have an intrinsic process structure, allowing dynamic notions such as bisimulation and back-and-forth games, and resource notions such as number of rounds of a game, to be defined. These are related to extensional or "static" structures via arboreal covers, which are resource-indexed comonadic adjunctions. These ideas are developed in a general, axiomatic setting, and applied to relational structures, where the comonadic constructions for pebbling, Ehrenfeucht-Fra\"iss\'e and modal bisimulation games recently introduced by Abramsky et al. are recovered, showing that many of the fundamental notions of finite model theory and descriptive complexity arise from instances of arboreal covers.
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spelling doaj.art-b8c1b105022b40a3aa9f29f6346507fb2024-03-08T10:42:53ZengLogical Methods in Computer Science e.V.Logical Methods in Computer Science1860-59742023-08-01Volume 19, Issue 310.46298/lmcs-19(3:14)20239839Arboreal Categories: An Axiomatic Theory of ResourcesSamson AbramskyLuca ReggioGame comonads provide a categorical syntax-free approach to finite model theory, and their Eilenberg-Moore coalgebras typically encode important combinatorial parameters of structures. In this paper, we develop a framework whereby the essential properties of these categories of coalgebras are captured in a purely axiomatic fashion. To this end, we introduce arboreal categories, which have an intrinsic process structure, allowing dynamic notions such as bisimulation and back-and-forth games, and resource notions such as number of rounds of a game, to be defined. These are related to extensional or "static" structures via arboreal covers, which are resource-indexed comonadic adjunctions. These ideas are developed in a general, axiomatic setting, and applied to relational structures, where the comonadic constructions for pebbling, Ehrenfeucht-Fra\"iss\'e and modal bisimulation games recently introduced by Abramsky et al. are recovered, showing that many of the fundamental notions of finite model theory and descriptive complexity arise from instances of arboreal covers.https://lmcs.episciences.org/9839/pdfcomputer science - logic in computer sciencemathematics - category theorymathematics - logic
spellingShingle Samson Abramsky
Luca Reggio
Arboreal Categories: An Axiomatic Theory of Resources
Logical Methods in Computer Science
computer science - logic in computer science
mathematics - category theory
mathematics - logic
title Arboreal Categories: An Axiomatic Theory of Resources
title_full Arboreal Categories: An Axiomatic Theory of Resources
title_fullStr Arboreal Categories: An Axiomatic Theory of Resources
title_full_unstemmed Arboreal Categories: An Axiomatic Theory of Resources
title_short Arboreal Categories: An Axiomatic Theory of Resources
title_sort arboreal categories an axiomatic theory of resources
topic computer science - logic in computer science
mathematics - category theory
mathematics - logic
url https://lmcs.episciences.org/9839/pdf
work_keys_str_mv AT samsonabramsky arborealcategoriesanaxiomatictheoryofresources
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