Regularity of $3$-Path Ideals of Trees and Unicyclic Graphs

Fuente: arXiv
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Main Authors: Kumar, Rajiv, Sarkar, Rajib
Format: Preprint
Published: 2025
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_version_ 1866916653525106688
author Kumar, Rajiv
Sarkar, Rajib
author_facet Kumar, Rajiv
Sarkar, Rajib
contents Let $G$ be a simple graph and $I_3(G)$ be its $3$-path ideal in the corresponding polynomial ring $R$. In this article, we prove that for an arbitrary graph $G$, $reg(R/I_3(G))$ is bounded below by $2ν_3(G)$, where $ν_3(G)$ denotes the $3$-path induced matching number of $G$. We give a class of graphs, namely, trees for which the lower bound is attained. Also, for a unicyclic graph $G$, we show that $reg(R/I_3(G))\leq 2ν_3(G)+2$ and provide an example that shows that the given upper bound is sharp.
format Preprint
id arxiv_https___arxiv_org_abs_2503_12111
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Regularity of $3$-Path Ideals of Trees and Unicyclic Graphs
Kumar, Rajiv
Sarkar, Rajib
Commutative Algebra
Combinatorics
13D02, 13C13, 05E40
Let $G$ be a simple graph and $I_3(G)$ be its $3$-path ideal in the corresponding polynomial ring $R$. In this article, we prove that for an arbitrary graph $G$, $reg(R/I_3(G))$ is bounded below by $2ν_3(G)$, where $ν_3(G)$ denotes the $3$-path induced matching number of $G$. We give a class of graphs, namely, trees for which the lower bound is attained. Also, for a unicyclic graph $G$, we show that $reg(R/I_3(G))\leq 2ν_3(G)+2$ and provide an example that shows that the given upper bound is sharp.
title Regularity of $3$-Path Ideals of Trees and Unicyclic Graphs
topic Commutative Algebra
Combinatorics
13D02, 13C13, 05E40
url https://arxiv.org/abs/2503.12111