Abstract <p>In this paper, we consider an asymptotic degree sequence denotedby <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\mathcal{D}=(d_{1},d_{2},\dots,d_{n})\)</EquationSource> <!--LobJMat2560676Hamoud-m3--> </InlineEquation>, where <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(d_{n}\geqslant\dots\geqslant d_{1}\)</EquationSource> <!--LobJMat2560676Hamoud-m4--> </InlineEquation>. The examination of topological indices ontrees provides a general overview through bounds that identify themaximum and minimum number of edges incident to each vertex in thegraph. We study the Albertson index, defined as <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(\sum_{uv\in E(G)}|d_{u}(G)-d_{v}(G)|\)</EquationSource> <!--LobJMat2560676Hamoud-m5--> </InlineEquation>, and the Sigma index <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\sigma(G)\)</EquationSource> <!--LobJMat2560676Hamoud-m6--> </InlineEquation> for atree <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(T\)</EquationSource> <!--LobJMat2560676Hamoud-m7--> </InlineEquation> with degree sequence <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(\mathcal{D}\)</EquationSource> <!--LobJMat2560676Hamoud-m8--> </InlineEquation>. Using the firstZagreb index <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(M_{1}(T)\)</EquationSource> <!--LobJMat2560676Hamoud-m9--> </InlineEquation>, we show that for a degree sequence of order<InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(n=4\)</EquationSource> <!--LobJMat2560676Hamoud-m10--> </InlineEquation>, the irregularity of a tree <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\(T\)</EquationSource> <!--LobJMat2560676Hamoud-m11--> </InlineEquation> is given by <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(\textrm{irr}(T)=M_{1}(T)^{2}-2\sqrt{M_{1}(T)}+\sum_{i=1}^{3}|d_{i}-d_{i+1}|-(d_{2}+d_{3})-1\)</EquationSource> <!--LobJMat2560676Hamoud-m12--> </InlineEquation>.</p>

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Topological Indices with Degree Sequence \(\boldsymbol{\mathcal{D}}\) of Tree

  • Jasem Hamoud,
  • Duaa Abdullah

摘要

Abstract

In this paper, we consider an asymptotic degree sequence denotedby \(\mathcal{D}=(d_{1},d_{2},\dots,d_{n})\) , where \(d_{n}\geqslant\dots\geqslant d_{1}\) . The examination of topological indices ontrees provides a general overview through bounds that identify themaximum and minimum number of edges incident to each vertex in thegraph. We study the Albertson index, defined as \(\sum_{uv\in E(G)}|d_{u}(G)-d_{v}(G)|\) , and the Sigma index \(\sigma(G)\) for atree \(T\) with degree sequence \(\mathcal{D}\) . Using the firstZagreb index \(M_{1}(T)\) , we show that for a degree sequence of order \(n=4\) , the irregularity of a tree \(T\) is given by \(\textrm{irr}(T)=M_{1}(T)^{2}-2\sqrt{M_{1}(T)}+\sum_{i=1}^{3}|d_{i}-d_{i+1}|-(d_{2}+d_{3})-1\) .