<p>For a commutative ring <i>R</i>,&#xa0; with non-zero zero divisors <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(Z^{*}(R)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mi>Z</mi> <mrow /> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> <mrow> <mo stretchy="false">(</mo> <mi>R</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>. The zero divisor graph <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\Gamma (R)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <mi>R</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> is a simple graph with vertex set <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(Z^{*}(R)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mmultiscripts> <mi>Z</mi> <mrow /> <mrow> <mrow /> <mo>∗</mo> </mrow> </mmultiscripts> <mrow> <mo stretchy="false">(</mo> <mi>R</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, and two distinct vertices <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(x,y\in V(\Gamma (R))\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo>,</mo> <mi>y</mi> <mo>∈</mo> <mi>V</mi> <mo stretchy="false">(</mo> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <mi>R</mi> <mo stretchy="false">)</mo> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> are adjacent if and only if <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(x\cdot y=0.\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>x</mi> <mo>·</mo> <mi>y</mi> <mo>=</mo> <mn>0</mn> <mo>.</mo> </mrow> </math></EquationSource> </InlineEquation> This article presents counter examples for the energy, the second Zagreb index, and the eigenvalues associated with zero divisor graphs of rings that were found in [Johnson and Sankar, J. Appl. Math. Comp. (2023)]. For the zero divisor graph <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(\mathbb {Z}_{p}[x]/\langle x^{4} \rangle \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="double-struck">Z</mi> <mi>p</mi> </msub> <mrow> <mo stretchy="false">[</mo> <mi>x</mi> <mo stretchy="false">]</mo> </mrow> <mo stretchy="false">/</mo> <mrow> <mo stretchy="false">⟨</mo> <msup> <mi>x</mi> <mn>4</mn> </msup> <mo stretchy="false">⟩</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, we rectify the eigenvalues (energy) and the Zagreb index results. We show that for any prime <i>p</i>, <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(\Gamma (\mathbb {Z}_{p}[x]/\langle x^{4} \rangle )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <msub> <mi mathvariant="double-struck">Z</mi> <mi>p</mi> </msub> <mrow> <mo stretchy="false">[</mo> <mi>x</mi> <mo stretchy="false">]</mo> </mrow> <mo stretchy="false">/</mo> <mrow> <mo stretchy="false">⟨</mo> <msup> <mi>x</mi> <mn>4</mn> </msup> <mo stretchy="false">⟩</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> is non-hyperenergetic and for prime <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\(p\ge 3\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mo>≥</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(\Gamma (\mathbb {Z}_{p}[x]/\langle x^{4} \rangle )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <msub> <mi mathvariant="double-struck">Z</mi> <mi>p</mi> </msub> <mrow> <mo stretchy="false">[</mo> <mi>x</mi> <mo stretchy="false">]</mo> </mrow> <mo stretchy="false">/</mo> <mrow> <mo stretchy="false">⟨</mo> <msup> <mi>x</mi> <mn>4</mn> </msup> <mo stretchy="false">⟩</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> is hypoenergetic. We give a formulae for the topological indices of <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(\Gamma (\mathbb {Z}_{p}[x]/\langle x^{4} \rangle )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="normal">Γ</mi> <mo stretchy="false">(</mo> <msub> <mi mathvariant="double-struck">Z</mi> <mi>p</mi> </msub> <mrow> <mo stretchy="false">[</mo> <mi>x</mi> <mo stretchy="false">]</mo> </mrow> <mo stretchy="false">/</mo> <mrow> <mo stretchy="false">⟨</mo> <msup> <mi>x</mi> <mn>4</mn> </msup> <mo stretchy="false">⟩</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> and show that its Zagreb indices satisfy Zagreb Conjecture [Hansen and Vukičcević, Croatica Chem. Acta, (2007)].</p>

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On the eigenvalues of zero divisor graphs associated with commutative rings

  • Bilal Ahmad Rather

摘要

For a commutative ring R,  with non-zero zero divisors \(Z^{*}(R)\) Z ( R ) . The zero divisor graph \(\Gamma (R)\) Γ ( R ) is a simple graph with vertex set \(Z^{*}(R)\) Z ( R ) , and two distinct vertices \(x,y\in V(\Gamma (R))\) x , y V ( Γ ( R ) ) are adjacent if and only if \(x\cdot y=0.\) x · y = 0 . This article presents counter examples for the energy, the second Zagreb index, and the eigenvalues associated with zero divisor graphs of rings that were found in [Johnson and Sankar, J. Appl. Math. Comp. (2023)]. For the zero divisor graph \(\mathbb {Z}_{p}[x]/\langle x^{4} \rangle \) Z p [ x ] / x 4 , we rectify the eigenvalues (energy) and the Zagreb index results. We show that for any prime p, \(\Gamma (\mathbb {Z}_{p}[x]/\langle x^{4} \rangle )\) Γ ( Z p [ x ] / x 4 ) is non-hyperenergetic and for prime \(p\ge 3\) p 3 , \(\Gamma (\mathbb {Z}_{p}[x]/\langle x^{4} \rangle )\) Γ ( Z p [ x ] / x 4 ) is hypoenergetic. We give a formulae for the topological indices of \(\Gamma (\mathbb {Z}_{p}[x]/\langle x^{4} \rangle )\) Γ ( Z p [ x ] / x 4 ) and show that its Zagreb indices satisfy Zagreb Conjecture [Hansen and Vukičcević, Croatica Chem. Acta, (2007)].