<p>Let <i>G</i> be a simple connected graph of order <i>n</i>. Denote by <i>D</i>(<i>G</i>) the distance matrix of <i>G</i> and by <i>Tr</i>(<i>G</i>) the diagonal matrix of its vertex transmissions. For <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_846_Article_IEq1.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="74" /> </InlineMediaObject> <EquationSource Format="TEX">\(0\le \alpha \le 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>0</mn> <mo>≤</mo> <mi>α</mi> <mo>≤</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>, the generalized distance matrix <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_846_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="49" /> </InlineMediaObject> <EquationSource Format="TEX">\(D_{\alpha }(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>D</mi> <mi>α</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> of <i>G</i> is defined as <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_846_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="240" /> </InlineMediaObject> <EquationSource Format="TEX">\(D_{\alpha }(G)=\alpha Tr(G)+(1-\alpha )D(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>D</mi> <mi>α</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mi>α</mi> <mi>T</mi> <mi>r</mi> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> <mo>+</mo> <mrow> <mo stretchy="false">(</mo> <mn>1</mn> <mo>-</mo> <mi>α</mi> <mo stretchy="false">)</mo> </mrow> <mi>D</mi> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>. The generalized distance energy of a graph <i>G</i> (energy of <i>G</i> with respect to the generalized distance matrix) is defined as <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_846_Article_IEq4.gif" Format="GIF" Height="33" Rendition="HTML" Resolution="72" Type="Linedraw" Width="221" /> </InlineMediaObject> <EquationSource Format="TEX">\(E^{D_{\alpha }}(G)=\sum _{i=1}^{n}\left| \partial _i-\frac{2\alpha W(G)}{n}\right| ,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>E</mi> <msub> <mi>D</mi> <mi>α</mi> </msub> </msup> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <msubsup> <mo>∑</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </msubsup> <mfenced close="|" open="|"> <msub> <mi>∂</mi> <mi>i</mi> </msub> <mo>-</mo> <mfrac> <mrow> <mn>2</mn> <mi>α</mi> <mi>W</mi> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> <mi>n</mi> </mfrac> </mfenced> <mo>,</mo> </mrow> </math></EquationSource> </InlineEquation> where <i>W</i>(<i>G</i>) is the transmission (also called the Wiener index) of a graph <i>G</i> and <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_846_Article_IEq5.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="138" /> </InlineMediaObject> <EquationSource Format="TEX">\(\partial _{1}\ge \partial _{2}\ge \cdots \ge \partial _{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>∂</mi> <mn>1</mn> </msub> <mo>≥</mo> <msub> <mi>∂</mi> <mn>2</mn> </msub> <mo>≥</mo> <mo>⋯</mo> <mo>≥</mo> <msub> <mi>∂</mi> <mi>n</mi> </msub> </mrow> </math></EquationSource> </InlineEquation> are the eigenvalues of <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_846_Article_IEq2.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="49" /> </InlineMediaObject> <EquationSource Format="TEX">\(D_{\alpha }(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>D</mi> <mi>α</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>. In this paper, we establish new upper and lower bounds for <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_846_Article_IEq7.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="58" /> </InlineMediaObject> <EquationSource Format="TEX">\(E^{D_{\alpha }}(G)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>E</mi> <msub> <mi>D</mi> <mi>α</mi> </msub> </msup> <mrow> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> in terms of various graph invariants, and we characterize the extremal graphs for which these bounds are attained.</p>

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Energy of graphs with respect to generalized distance matrix: Extremal results and bounds

  • Abdollah Alhevaz,
  • Maryam Baghipur,
  • Kinkar Chandra Das,
  • Yilun Shang

摘要

Let G be a simple connected graph of order n. Denote by D(G) the distance matrix of G and by Tr(G) the diagonal matrix of its vertex transmissions. For \(0\le \alpha \le 1\) 0 α 1 , the generalized distance matrix \(D_{\alpha }(G)\) D α ( G ) of G is defined as \(D_{\alpha }(G)=\alpha Tr(G)+(1-\alpha )D(G)\) D α ( G ) = α T r ( G ) + ( 1 - α ) D ( G ) . The generalized distance energy of a graph G (energy of G with respect to the generalized distance matrix) is defined as \(E^{D_{\alpha }}(G)=\sum _{i=1}^{n}\left| \partial _i-\frac{2\alpha W(G)}{n}\right| ,\) E D α ( G ) = i = 1 n i - 2 α W ( G ) n , where W(G) is the transmission (also called the Wiener index) of a graph G and \(\partial _{1}\ge \partial _{2}\ge \cdots \ge \partial _{n}\) 1 2 n are the eigenvalues of \(D_{\alpha }(G)\) D α ( G ) . In this paper, we establish new upper and lower bounds for \(E^{D_{\alpha }}(G)\) E D α ( G ) in terms of various graph invariants, and we characterize the extremal graphs for which these bounds are attained.