Critical groups of arithmetical structures under a generalized star-clique operation

Fuente: arXiv
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Main Authors: Diaz-Lopez, Alexander, Louwsma, Joel
Format: Preprint
Published: 2022
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author Diaz-Lopez, Alexander
Louwsma, Joel
author_facet Diaz-Lopez, Alexander
Louwsma, Joel
contents An arithmetical structure on a finite, connected graph without loops is given by an assignment of positive integers to the vertices such that, at each vertex, the integer there is a divisor of the sum of the integers at adjacent vertices, counted with multiplicity if the graph is not simple. Associated to each arithmetical structure is a finite abelian group known as its critical group. Keyes and Reiter gave an operation that takes in an arithmetical structure on a finite, connected graph without loops and produces an arithmetical structure on a graph with one fewer vertex. We study how this operation transforms critical groups. We bound the order and the invariant factors of the resulting critical group in terms of the original arithmetical structure and critical group. When the original graph is simple, we determine the resulting critical group exactly.
format Preprint
id arxiv_https___arxiv_org_abs_2206_14836
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Critical groups of arithmetical structures under a generalized star-clique operation
Diaz-Lopez, Alexander
Louwsma, Joel
Combinatorics
Number Theory
Rings and Algebras
05C50 (Primary) 05C25, 11C20, 15B36, 20K01 (Secondary)
An arithmetical structure on a finite, connected graph without loops is given by an assignment of positive integers to the vertices such that, at each vertex, the integer there is a divisor of the sum of the integers at adjacent vertices, counted with multiplicity if the graph is not simple. Associated to each arithmetical structure is a finite abelian group known as its critical group. Keyes and Reiter gave an operation that takes in an arithmetical structure on a finite, connected graph without loops and produces an arithmetical structure on a graph with one fewer vertex. We study how this operation transforms critical groups. We bound the order and the invariant factors of the resulting critical group in terms of the original arithmetical structure and critical group. When the original graph is simple, we determine the resulting critical group exactly.
title Critical groups of arithmetical structures under a generalized star-clique operation
topic Combinatorics
Number Theory
Rings and Algebras
05C50 (Primary) 05C25, 11C20, 15B36, 20K01 (Secondary)
url https://arxiv.org/abs/2206.14836