On connected graphs with finite spectral redundancy index and Pythagorean triplets

Fuente: arXiv
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Autori principali: Kumar, Pawan, Pirzada, S., Merajuddin, S.
Natura: Preprint
Pubblicazione: 2025
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author Kumar, Pawan
Pirzada, S.
Merajuddin, S.
author_facet Kumar, Pawan
Pirzada, S.
Merajuddin, S.
contents This article investigates spectral redundancy, a concept initially introduced by Alberto Seeger. Spectral redundancy arises when different connected induced subgraphs of a graph share the same spectral radius in their adjacency spectrum. Let \(b(G)\) denote the total number of non-isomorphic induced subgraphs of \(G\), and \(c(G)\) represents the cardinality of the set of spectral radius of all connected induced subgraphs of \(G\). The spectral redundancy of a graph \( G \) is defined as the ratio \( \frac{b(G)}{c(G)} \). The supremum of this ratio across all graphs in a family is called the spectral redundancy index of that family. We focus on a family of graphs that exhibit spectral redundancy and we find out the spectral redundancy index of this family. Furthermore, we investigate the connection between the spectral redundancy of these graphs and the presence of Pythagorean triplets.
format Preprint
id arxiv_https___arxiv_org_abs_2507_11555
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On connected graphs with finite spectral redundancy index and Pythagorean triplets
Kumar, Pawan
Pirzada, S.
Merajuddin, S.
Combinatorics
05C50, 15A42
This article investigates spectral redundancy, a concept initially introduced by Alberto Seeger. Spectral redundancy arises when different connected induced subgraphs of a graph share the same spectral radius in their adjacency spectrum. Let \(b(G)\) denote the total number of non-isomorphic induced subgraphs of \(G\), and \(c(G)\) represents the cardinality of the set of spectral radius of all connected induced subgraphs of \(G\). The spectral redundancy of a graph \( G \) is defined as the ratio \( \frac{b(G)}{c(G)} \). The supremum of this ratio across all graphs in a family is called the spectral redundancy index of that family. We focus on a family of graphs that exhibit spectral redundancy and we find out the spectral redundancy index of this family. Furthermore, we investigate the connection between the spectral redundancy of these graphs and the presence of Pythagorean triplets.
title On connected graphs with finite spectral redundancy index and Pythagorean triplets
topic Combinatorics
05C50, 15A42
url https://arxiv.org/abs/2507.11555