<p>Given a partition <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq1.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">\(\lambda \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>λ</mi> </math></EquationSource> </InlineEquation>, we write <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="38" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_j(\lambda )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>e</mi> <mi>j</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>λ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> for the <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq3.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="22" /> </InlineMediaObject> <EquationSource Format="TEX">\(j^{\text {th}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mi>j</mi> <mtext>th</mtext> </msup> </math></EquationSource> </InlineEquation> elementary symmetric polynomial <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq4.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="16" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_j\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>e</mi> <mi>j</mi> </msub> </math></EquationSource> </InlineEquation> evaluated at the parts of <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq5.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">\(\lambda \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>λ</mi> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq6.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="56" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_jp_A(n)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>e</mi> <mi>j</mi> </msub> <msub> <mi>p</mi> <mi>A</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> for the sum of <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq7.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="38" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_j(\lambda )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>e</mi> <mi>j</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>λ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> as <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq8.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">\(\lambda \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>λ</mi> </math></EquationSource> </InlineEquation> ranges over the set of partitions of <i>n</i> with parts in <i>A</i>. For <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq9.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="56" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_jp_A(n)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>e</mi> <mi>j</mi> </msub> <msub> <mi>p</mi> <mi>A</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, we prove analogs of the classical formula for the partition function, <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq10.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="227" /> </InlineMediaObject> <EquationSource Format="TEX">\(p(n)=1/n \sum _{k=0}^{n-1}\sigma _1(n-k)p(k)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mn>1</mn> <mo stretchy="false">/</mo> <mi>n</mi> <msubsup> <mo>∑</mo> <mrow> <mi>k</mi> <mo>=</mo> <mn>0</mn> </mrow> <mrow> <mi>n</mi> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <msub> <mi>σ</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo>-</mo> <mi>k</mi> <mo stretchy="false">)</mo> </mrow> <mi>p</mi> <mrow> <mo stretchy="false">(</mo> <mi>k</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq11"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq11.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="17" /> </InlineMediaObject> <EquationSource Format="TEX">\(\sigma _1\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>σ</mi> <mn>1</mn> </msub> </math></EquationSource> </InlineEquation> is the sum of divisors function. We prove several congruences for <InlineEquation ID="IEq12"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq12.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="53" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_2p_4(n)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>e</mi> <mn>2</mn> </msub> <msub> <mi>p</mi> <mn>4</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, the sum of <InlineEquation ID="IEq13"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq13.gif" Format="GIF" Height="12" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_2\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>e</mi> <mn>2</mn> </msub> </math></EquationSource> </InlineEquation> over the set of partitions of <i>n</i> into four parts. Define the function <InlineEquation ID="IEq14"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq14.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="52" /> </InlineMediaObject> <EquationSource Format="TEX">\(\text {pre}_j(\lambda )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>pre</mtext> <mi>j</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>λ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> to be the multiset of monomials in <InlineEquation ID="IEq15"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq15.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="38" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_j(\lambda )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>e</mi> <mi>j</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>λ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, which is itself a partition. If <InlineEquation ID="IEq16"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq16.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="18" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {A}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">A</mi> </math></EquationSource> </InlineEquation> is a set of partitions, we define <InlineEquation ID="IEq17"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq17.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="56" /> </InlineMediaObject> <EquationSource Format="TEX">\(\text {pre}_j({\mathcal {A}})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>pre</mtext> <mi>j</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">A</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> to be the set of partitions <InlineEquation ID="IEq18"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq18.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="52" /> </InlineMediaObject> <EquationSource Format="TEX">\(\text {pre}_j(\lambda )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>pre</mtext> <mi>j</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>λ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> as <InlineEquation ID="IEq19"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq19.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="15" /> </InlineMediaObject> <EquationSource Format="TEX">\(\lambda \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>λ</mi> </math></EquationSource> </InlineEquation> ranges over <InlineEquation ID="IEq20"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq20.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="18" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {A}}\)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="script">A</mi> </math></EquationSource> </InlineEquation>. If <InlineEquation ID="IEq21"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq21.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="37" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {P}}(n)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="script">P</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> is the set of all partitions of <i>n</i>, we conjecture that the number of odd partitions in <InlineEquation ID="IEq22"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq22.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="78" /> </InlineMediaObject> <EquationSource Format="TEX">\(\text {pre}_2({\mathcal {P}}(n))\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>pre</mtext> <mn>2</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">P</mi> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> is at least the number of distinct partitions. We prove some results about <InlineEquation ID="IEq23"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq23.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="77" /> </InlineMediaObject> <EquationSource Format="TEX">\(\text {pre}_2({\mathcal {B}}(n))\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mtext>pre</mtext> <mn>2</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi mathvariant="script">B</mi> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq24"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq24.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="36" /> </InlineMediaObject> <EquationSource Format="TEX">\({\mathcal {B}}(n)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi mathvariant="script">B</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> is the set of binary partitions of <i>n</i>. We conclude with conjectures on the log-concavity of functions related to <InlineEquation ID="IEq25"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq25.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="46" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_jp(n)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>e</mi> <mi>j</mi> </msub> <mi>p</mi> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, the sum of <InlineEquation ID="IEq26"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq26.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="38" /> </InlineMediaObject> <EquationSource Format="TEX">\(e_j(\lambda )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>e</mi> <mi>j</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>λ</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> for all <InlineEquation ID="IEq27"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11139_2024_1001_Article_IEq27.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="68" /> </InlineMediaObject> <EquationSource Format="TEX">\(\lambda \in {\mathcal {P}}(n)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>λ</mi> <mo>∈</mo> <mi mathvariant="script">P</mi> <mo stretchy="false">(</mo> <mi>n</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>.</p>

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Partitions and elementary symmetric polynomials: an experimental approach

  • Cristina Ballantine,
  • George Beck,
  • Mircea Merca

摘要

Given a partition \(\lambda \) λ , we write \(e_j(\lambda )\) e j ( λ ) for the \(j^{\text {th}}\) j th elementary symmetric polynomial \(e_j\) e j evaluated at the parts of \(\lambda \) λ and \(e_jp_A(n)\) e j p A ( n ) for the sum of \(e_j(\lambda )\) e j ( λ ) as \(\lambda \) λ ranges over the set of partitions of n with parts in A. For \(e_jp_A(n)\) e j p A ( n ) , we prove analogs of the classical formula for the partition function, \(p(n)=1/n \sum _{k=0}^{n-1}\sigma _1(n-k)p(k)\) p ( n ) = 1 / n k = 0 n - 1 σ 1 ( n - k ) p ( k ) , where \(\sigma _1\) σ 1 is the sum of divisors function. We prove several congruences for \(e_2p_4(n)\) e 2 p 4 ( n ) , the sum of \(e_2\) e 2 over the set of partitions of n into four parts. Define the function \(\text {pre}_j(\lambda )\) pre j ( λ ) to be the multiset of monomials in \(e_j(\lambda )\) e j ( λ ) , which is itself a partition. If \({\mathcal {A}}\) A is a set of partitions, we define \(\text {pre}_j({\mathcal {A}})\) pre j ( A ) to be the set of partitions \(\text {pre}_j(\lambda )\) pre j ( λ ) as \(\lambda \) λ ranges over \({\mathcal {A}}\) A . If \({\mathcal {P}}(n)\) P ( n ) is the set of all partitions of n, we conjecture that the number of odd partitions in \(\text {pre}_2({\mathcal {P}}(n))\) pre 2 ( P ( n ) ) is at least the number of distinct partitions. We prove some results about \(\text {pre}_2({\mathcal {B}}(n))\) pre 2 ( B ( n ) ) , where \({\mathcal {B}}(n)\) B ( n ) is the set of binary partitions of n. We conclude with conjectures on the log-concavity of functions related to \(e_jp(n)\) e j p ( n ) , the sum of \(e_j(\lambda )\) e j ( λ ) for all \(\lambda \in {\mathcal {P}}(n)\) λ P ( n ) .