<p>We study the asymptotic behaviour of <i>v</i>-number and local <i>v</i>-numbers of Noetherian generalized symbolic power filtrations <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\mathcal {I}}=\{I_n\}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="script">I</mi> <mo>=</mo> <mo stretchy="false">{</mo> <msub> <mi>I</mi> <mi>n</mi> </msub> <mo stretchy="false">}</mo> </mrow> </math></EquationSource> </InlineEquation> in a Noetherian <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\mathbb N}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="double-struck">N</mi> </math></EquationSource> </InlineEquation>-graded domain and show that they are quasi-linear type. We provide sufficient conditions for the existence of the limits <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\lim \limits _{n\rightarrow \infty }\frac{v(I_n)}{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <munder> <mo movablelimits="false">lim</mo> <mrow> <mi>n</mi> <mo stretchy="false">→</mo> <mi>∞</mi> </mrow> </munder> <mfrac> <mrow> <mi>v</mi> <mo stretchy="false">(</mo> <msub> <mi>I</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mi>n</mi> </mfrac> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(\lim \limits _{n\rightarrow \infty }\frac{v_{\mathfrak {p}}(I_n)}{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <munder> <mo movablelimits="false">lim</mo> <mrow> <mi>n</mi> <mo stretchy="false">→</mo> <mi>∞</mi> </mrow> </munder> <mfrac> <mrow> <msub> <mi>v</mi> <mi mathvariant="fraktur">p</mi> </msub> <mrow> <mo stretchy="false">(</mo> <msub> <mi>I</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> </mrow> <mi>n</mi> </mfrac> </mrow> </math></EquationSource> </InlineEquation> for all <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\({\mathfrak {p}}\in {\overline{A}}({\mathcal {I}})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="fraktur">p</mi> <mo>∈</mo> <mover> <mi>A</mi> <mo>¯</mo> </mover> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">I</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>. We explicitly compute local <i>v</i>-numbers and <i>v</i>-numbers of symbolic powers of cover ideals of complete bipartite graphs, complete graphs, cycles, <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(K_m^s\)</EquationSource> <EquationSource Format="MATHML"><math> <msubsup> <mi>K</mi> <mi>m</mi> <mi>s</mi> </msubsup> </math></EquationSource> </InlineEquation> and compare them with their Castelnuovo–Mumford regularity. For every positive integer <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\(p\ge 2\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mo>≥</mo> <mn>2</mn> </mrow> </math></EquationSource> </InlineEquation>, we provide an example of an unmixed bipartite graph <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\({\mathcal {H}}_p\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">H</mi> <mi>p</mi> </msub> </math></EquationSource> </InlineEquation> that is not a complete multipartite graph and <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(v(J({\mathcal {H}}_p))\ge \operatorname {bight}(I({\mathcal {H}}_p))\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>v</mi> <mrow> <mo stretchy="false">(</mo> <mi>J</mi> <mrow> <mo stretchy="false">(</mo> <msub> <mi mathvariant="script">H</mi> <mi>p</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">)</mo> </mrow> <mo>≥</mo> <mo>bight</mo> <mrow> <mo stretchy="false">(</mo> <mi>I</mi> <mrow> <mo stretchy="false">(</mo> <msub> <mi mathvariant="script">H</mi> <mi>p</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>. This answers a question of Saha in (Int Math Res Not IMRN 11:9010–9019, 2024, Question 3.12). We show that for both connected bipartite graphs and connected non-bipartite graphs, the difference between the regularity and the <i>v</i>-number of the cover ideals can be arbitrarily large. This strengthens and gives an alternative proof of Saha in (Int Math Res Not IMRN 11:9010-9019, 2024, Theorem 3.10).</p>

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v-Numbers of symbolic power filtrations

  • Vanmathi A,
  • Parangama Sarkar

摘要

We study the asymptotic behaviour of v-number and local v-numbers of Noetherian generalized symbolic power filtrations \({\mathcal {I}}=\{I_n\}\) I = { I n } in a Noetherian \({\mathbb N}\) N -graded domain and show that they are quasi-linear type. We provide sufficient conditions for the existence of the limits \(\lim \limits _{n\rightarrow \infty }\frac{v(I_n)}{n}\) lim n v ( I n ) n and \(\lim \limits _{n\rightarrow \infty }\frac{v_{\mathfrak {p}}(I_n)}{n}\) lim n v p ( I n ) n for all \({\mathfrak {p}}\in {\overline{A}}({\mathcal {I}})\) p A ¯ ( I ) . We explicitly compute local v-numbers and v-numbers of symbolic powers of cover ideals of complete bipartite graphs, complete graphs, cycles, \(K_m^s\) K m s and compare them with their Castelnuovo–Mumford regularity. For every positive integer \(p\ge 2\) p 2 , we provide an example of an unmixed bipartite graph \({\mathcal {H}}_p\) H p that is not a complete multipartite graph and \(v(J({\mathcal {H}}_p))\ge \operatorname {bight}(I({\mathcal {H}}_p))\) v ( J ( H p ) ) bight ( I ( H p ) ) . This answers a question of Saha in (Int Math Res Not IMRN 11:9010–9019, 2024, Question 3.12). We show that for both connected bipartite graphs and connected non-bipartite graphs, the difference between the regularity and the v-number of the cover ideals can be arbitrarily large. This strengthens and gives an alternative proof of Saha in (Int Math Res Not IMRN 11:9010-9019, 2024, Theorem 3.10).