<p>Let <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\((P, \le )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>P</mi> <mo>,</mo> <mo>≤</mo> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> be a partially ordered set with minimum element 0 and for every <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(x, y \in P\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>∈</mo> <mi>P</mi> </mrow> </math></EquationSource> </InlineEquation> set <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(L(x,y) = \{z \in P \mid z \le x \text { and } z \le y\}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>L</mi> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">{</mo> <mi>z</mi> <mo>∈</mo> <mi>P</mi> <mo>∣</mo> <mi>z</mi> <mo>≤</mo> <mi>x</mi> <mspace width="0.333333em" /> <mtext>and</mtext> <mspace width="0.333333em" /> <mi>z</mi> <mo>≤</mo> <mi>y</mi> <mo stretchy="false">}</mo> </mrow> </math></EquationSource> </InlineEquation>. An element <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(x \in P\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo>∈</mo> <mi>P</mi> </mrow> </math></EquationSource> </InlineEquation> is called a zero-divisor of <i>P</i> if <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(L(x,y) = \{ 0 \}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>L</mi> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">{</mo> <mn>0</mn> <mo stretchy="false">}</mo> </mrow> </math></EquationSource> </InlineEquation> for some <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(0 \ne y \in P\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>0</mn> <mo>≠</mo> <mi>y</mi> <mo>∈</mo> <mi>P</mi> </mrow> </math></EquationSource> </InlineEquation>. The zero-divisor graph <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\Gamma (P)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <mi>P</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> of <i>P</i> is obtained by letting all nonzero zero-divisors of <i>P</i> to be the vertices and defining distinct vertices <i>x</i> and <i>y</i> to be adjacent if and only if <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(L(x,y) = \{ 0 \}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>L</mi> <mo stretchy="false">(</mo> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo stretchy="false">)</mo> <mo>=</mo> <mo stretchy="false">{</mo> <mn>0</mn> <mo stretchy="false">}</mo> </mrow> </math></EquationSource> </InlineEquation>. In this paper, we give a comprehensive characterization of well-coveredness, very well-coveredness, Cohen–Macaulayness and Gorensteinness for the zero-divisor graphs of divisor posets.</p>

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Cohen–Macaulay and Gorenstein zero-divisor graphs of divisor posets

  • T. Asir,
  • P. V. Cheri,
  • M. R. Pournaki,
  • M. Poursoltani

摘要

Let \((P, \le )\) ( P , ) be a partially ordered set with minimum element 0 and for every \(x, y \in P\) x , y P set \(L(x,y) = \{z \in P \mid z \le x \text { and } z \le y\}\) L ( x , y ) = { z P z x and z y } . An element \(x \in P\) x P is called a zero-divisor of P if \(L(x,y) = \{ 0 \}\) L ( x , y ) = { 0 } for some \(0 \ne y \in P\) 0 y P . The zero-divisor graph \(\Gamma (P)\) Γ ( P ) of P is obtained by letting all nonzero zero-divisors of P to be the vertices and defining distinct vertices x and y to be adjacent if and only if \(L(x,y) = \{ 0 \}\) L ( x , y ) = { 0 } . In this paper, we give a comprehensive characterization of well-coveredness, very well-coveredness, Cohen–Macaulayness and Gorensteinness for the zero-divisor graphs of divisor posets.