<p>For a simple graph <i>G</i>, let <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="9_2025_2949_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="22" /> </InlineMediaObject> <EquationSource Format="TEX">\(J_G\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>J</mi> <mi>G</mi> </msub> </math></EquationSource> </InlineEquation> denote the corresponding binomial edge ideal. This article considers the binomial edge ideal of the corona product of two connected graphs <i>G</i> and <i>H</i>. The corona product of <i>G</i> and <i>H</i>, denoted by <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="9_2025_2949_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="48" /> </InlineMediaObject> <EquationSource Format="TEX">\(G\circ H\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>G</mi> <mo>∘</mo> <mi>H</mi> </mrow> </math></EquationSource> </InlineEquation>, is a construction where each vertex of <i>G</i> is connected (via the coning-off) to an entire copy of <i>H</i>. This is a direct generalization of a cone construction. Previous studies have shown that for <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="9_2025_2949_Article_IEq3.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="38" /> </InlineMediaObject> <EquationSource Format="TEX">\(J_{G \circ H}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>J</mi> <mrow> <mi>G</mi> <mo>∘</mo> <mi>H</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> to be Cohen–Macaulay, both <i>G</i> and <i>H</i> must be complete graphs. However, there are no general formulae for the dimension, depth, or Castelnuovo–Mumford regularity of <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="9_2025_2949_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="38" /> </InlineMediaObject> <EquationSource Format="TEX">\(J_{G\circ H}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>J</mi> <mrow> <mi>G</mi> <mo>∘</mo> <mi>H</mi> </mrow> </msub> </math></EquationSource> </InlineEquation> for all graphs <i>G</i> and <i>H</i>. In this article, we provide a general formula for the dimension, depth and Castelnuovo–Mumford regularity of the binomial edge ideals of certain corona and corona-type (somewhat a generalization of corona) products of special interests. Additionally, we study the Cohen–Macaulayness, unmixedness and related properties of binomial edge ideals corresponding to above class of graphs. We have also added a short note on the reduction of the Bolognini–Macchia–Strazzanti conjecture to all graphs with a diameter of 3.</p>

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On Binomial Edge Ideals of Corona of Graphs

  • Buddhadev Hajra,
  • Rajib Sarkar

摘要

For a simple graph G, let \(J_G\) J G denote the corresponding binomial edge ideal. This article considers the binomial edge ideal of the corona product of two connected graphs G and H. The corona product of G and H, denoted by \(G\circ H\) G H , is a construction where each vertex of G is connected (via the coning-off) to an entire copy of H. This is a direct generalization of a cone construction. Previous studies have shown that for \(J_{G \circ H}\) J G H to be Cohen–Macaulay, both G and H must be complete graphs. However, there are no general formulae for the dimension, depth, or Castelnuovo–Mumford regularity of \(J_{G\circ H}\) J G H for all graphs G and H. In this article, we provide a general formula for the dimension, depth and Castelnuovo–Mumford regularity of the binomial edge ideals of certain corona and corona-type (somewhat a generalization of corona) products of special interests. Additionally, we study the Cohen–Macaulayness, unmixedness and related properties of binomial edge ideals corresponding to above class of graphs. We have also added a short note on the reduction of the Bolognini–Macchia–Strazzanti conjecture to all graphs with a diameter of 3.