<p>The rate of a standard graded <i>K</i>-algebra <i>A</i> is a measure of the growth of the shifts in a minimal free resolution of <i>K</i> as an <i>A</i>-module. In particular <i>A</i> has rate one if and only if it is Koszul. It is known that a generic Artinian Gorenstein algebra of embedding dimension <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="209_2025_3798_Article_IEq1.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(n \ge 3\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>≥</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation> and socle degree <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="209_2025_3798_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="40" /> </InlineMediaObject> <EquationSource Format="TEX">\(s=3\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>s</mi> <mo>=</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation> is Koszul. We prove that a generic Artinian Gorenstein algebra with <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="209_2025_3798_Article_IEq3.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\(n\ge 4\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>≥</mo> <mn>4</mn> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="209_2025_3798_Article_IEq4.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="41" /> </InlineMediaObject> <EquationSource Format="TEX">\(s \ge 3 \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>s</mi> <mo>≥</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation> has rate <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="209_2025_3798_Article_IEq5.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="34" /> </InlineMediaObject> <EquationSource Format="TEX">\(\left\lfloor \frac{s}{2} \right\rfloor .\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mfenced close="⌋" open="⌊"> <mfrac> <mi>s</mi> <mn>2</mn> </mfrac> </mfenced> <mo>.</mo> </mrow> </math></EquationSource> </InlineEquation> In the process we show that such an algebra is generated in degree <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="209_2025_3798_Article_IEq6.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="59" /> </InlineMediaObject> <EquationSource Format="TEX">\(\left\lfloor \frac{s}{2} \right\rfloor +1.\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mfenced close="⌋" open="⌊"> <mfrac> <mi>s</mi> <mn>2</mn> </mfrac> </mfenced> <mo>+</mo> <mn>1</mn> <mo>.</mo> </mrow> </math></EquationSource> </InlineEquation> This gives a partial positive answer to a longstanding conjecture stated by the first author on the minimal free resolution of a generic Artinian Gorenstein ring of odd socle degree.</p>

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On the rate of generic Gorenstein K-algebras

  • Mats Boij,
  • Emanuela De Negri,
  • Alessandro De Stefani,
  • Maria Evelina Rossi

摘要

The rate of a standard graded K-algebra A is a measure of the growth of the shifts in a minimal free resolution of K as an A-module. In particular A has rate one if and only if it is Koszul. It is known that a generic Artinian Gorenstein algebra of embedding dimension \(n \ge 3\) n 3 and socle degree \(s=3\) s = 3 is Koszul. We prove that a generic Artinian Gorenstein algebra with \(n\ge 4\) n 4 and \(s \ge 3 \) s 3 has rate \(\left\lfloor \frac{s}{2} \right\rfloor .\) s 2 . In the process we show that such an algebra is generated in degree \(\left\lfloor \frac{s}{2} \right\rfloor +1.\) s 2 + 1 . This gives a partial positive answer to a longstanding conjecture stated by the first author on the minimal free resolution of a generic Artinian Gorenstein ring of odd socle degree.