Connected components and non-bipartiteness of generalized Paley graphs

Fuente: arXiv
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Main Authors: Podestá, Ricardo A., Videla, Denis E.
Format: Preprint
Published: 2024
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author Podestá, Ricardo A.
Videla, Denis E.
author_facet Podestá, Ricardo A.
Videla, Denis E.
contents In this work we consider the class of Cayley graphs known as generalized Paley graphs (GP-graphs for short) given by $Γ(k,q) = Cay(\mathbb{F}_q, \{x^k : x\in \mathbb{F}_q^* \})$, where $\mathbb{F}_q$ is a finite field with $q$ elements, both in the directed and undirected case. Hence $q=p^m$ with $p$ prime, $m\in \mathbb{N}$ and one can assume that $k\mid q-1$. We first give the connected components of an arbitrary GP-graph. We show that these components are smaller GP-graphs all isomorphic to each other (generalizing a Lim and Praeger's result from 2009 to the directed case). We then characterize those GP-graphs which are disjoint unions of odd cycles. Finally, we show that $Γ(k,q)$ is non-bipartite except for the graphs $Γ(2^m-1,2^m)$, $m \in \mathbb{N}$, which are isomorphic to $K_2 \sqcup \cdots \sqcup K_2$, the disjoint union of $2^{m-1}$ copies of $K_2$.
format Preprint
id arxiv_https___arxiv_org_abs_2410_00281
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Connected components and non-bipartiteness of generalized Paley graphs
Podestá, Ricardo A.
Videla, Denis E.
Combinatorics
Primary 05C25, Secondary 05C50, 05C75, 05C20, 05C40
In this work we consider the class of Cayley graphs known as generalized Paley graphs (GP-graphs for short) given by $Γ(k,q) = Cay(\mathbb{F}_q, \{x^k : x\in \mathbb{F}_q^* \})$, where $\mathbb{F}_q$ is a finite field with $q$ elements, both in the directed and undirected case. Hence $q=p^m$ with $p$ prime, $m\in \mathbb{N}$ and one can assume that $k\mid q-1$. We first give the connected components of an arbitrary GP-graph. We show that these components are smaller GP-graphs all isomorphic to each other (generalizing a Lim and Praeger's result from 2009 to the directed case). We then characterize those GP-graphs which are disjoint unions of odd cycles. Finally, we show that $Γ(k,q)$ is non-bipartite except for the graphs $Γ(2^m-1,2^m)$, $m \in \mathbb{N}$, which are isomorphic to $K_2 \sqcup \cdots \sqcup K_2$, the disjoint union of $2^{m-1}$ copies of $K_2$.
title Connected components and non-bipartiteness of generalized Paley graphs
topic Combinatorics
Primary 05C25, Secondary 05C50, 05C75, 05C20, 05C40
url https://arxiv.org/abs/2410.00281