Diameters of endomorphism monoids of chains

Fuente: arXiv
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Hauptverfasser: East, James, Gould, Victoria, Miller, Craig, Quinn-Gregson, Thomas
Format: Preprint
Veröffentlicht: 2024
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author East, James
Gould, Victoria
Miller, Craig
Quinn-Gregson, Thomas
author_facet East, James
Gould, Victoria
Miller, Craig
Quinn-Gregson, Thomas
contents The left and right diameters of a monoid are topological invariants defined in terms of suprema of lengths of derivation sequences with respect to finite generating sets for the universal left or right congruences. We compute these parameters for the endomorphism monoid $End(C)$ of a chain $C$. Specifically, if $C$ is infinite then the left diameter of $End(C)$ is 2, while the right diameter is either 2 or 3, with the latter equal to 2 precisely when $C$ is a quotient of $C{\setminus}\{z\}$ for some endpoint $z$. If $C$ is finite then so is $End(C),$ in which case the left and right diameters are 1 (if $C$ is non-trivial) or 0.
format Preprint
id arxiv_https___arxiv_org_abs_2408_00416
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Diameters of endomorphism monoids of chains
East, James
Gould, Victoria
Miller, Craig
Quinn-Gregson, Thomas
Rings and Algebras
Combinatorics
The left and right diameters of a monoid are topological invariants defined in terms of suprema of lengths of derivation sequences with respect to finite generating sets for the universal left or right congruences. We compute these parameters for the endomorphism monoid $End(C)$ of a chain $C$. Specifically, if $C$ is infinite then the left diameter of $End(C)$ is 2, while the right diameter is either 2 or 3, with the latter equal to 2 precisely when $C$ is a quotient of $C{\setminus}\{z\}$ for some endpoint $z$. If $C$ is finite then so is $End(C),$ in which case the left and right diameters are 1 (if $C$ is non-trivial) or 0.
title Diameters of endomorphism monoids of chains
topic Rings and Algebras
Combinatorics
url https://arxiv.org/abs/2408.00416