Filtered colimit elimination from Birkhoff's variety theorem

Fuente: arXiv
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Autore principale: Kawase, Yuto
Natura: Preprint
Pubblicazione: 2023
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author Kawase, Yuto
author_facet Kawase, Yuto
contents Birkhoff's variety theorem, a fundamental theorem of universal algebra, asserts that a subclass of a given algebra is definable by equations if and only if it satisfies specific closure properties. In a generalized version of this theorem, closure under filtered colimits is required. However, in some special cases, such as finite-sorted equational theories and ordered algebraic theories, the theorem holds without assuming closure under filtered colimits. We call this phenomenon "filtered colimit elimination," and study a sufficient condition for it. We show that if a locally finitely presentable category $\mathscr{A}$ satisfies a noetherian-like condition, then filtered colimit elimination holds in the generalized Birkhoff's theorem for algebras relative to $\mathscr{A}$.
format Preprint
id arxiv_https___arxiv_org_abs_2309_05304
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Filtered colimit elimination from Birkhoff's variety theorem
Kawase, Yuto
Category Theory
18C10, 18C35, 18E45
Birkhoff's variety theorem, a fundamental theorem of universal algebra, asserts that a subclass of a given algebra is definable by equations if and only if it satisfies specific closure properties. In a generalized version of this theorem, closure under filtered colimits is required. However, in some special cases, such as finite-sorted equational theories and ordered algebraic theories, the theorem holds without assuming closure under filtered colimits. We call this phenomenon "filtered colimit elimination," and study a sufficient condition for it. We show that if a locally finitely presentable category $\mathscr{A}$ satisfies a noetherian-like condition, then filtered colimit elimination holds in the generalized Birkhoff's theorem for algebras relative to $\mathscr{A}$.
title Filtered colimit elimination from Birkhoff's variety theorem
topic Category Theory
18C10, 18C35, 18E45
url https://arxiv.org/abs/2309.05304