Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.04.048
Zhenyu Zhou , Xiaoping Xu
{"title":"Full conformal oscillator representations of odd orthogonal Lie algebras and combinatorial identities","authors":"Zhenyu Zhou , Xiaoping Xu","doi":"10.1016/j.jalgebra.2025.04.048","DOIUrl":"10.1016/j.jalgebra.2025.04.048","url":null,"abstract":"<div><div>Zhao and the second author (2013) constructed a functor from <span><math><mi>o</mi><mo>(</mo><mi>k</mi><mo>)</mo></math></span>-<strong>Mod</strong> to <span><math><mi>o</mi><mo>(</mo><mi>k</mi><mo>+</mo><mn>2</mn><mo>)</mo></math></span>-<strong>Mod</strong>. In this paper, we use the functor successively to obtain an inhomogeneous first-order differential operator realization for any highest-weight representation of <span><math><mi>o</mi><mo>(</mo><mn>2</mn><mi>n</mi><mo>+</mo><mn>3</mn><mo>)</mo></math></span> in <span><math><msup><mrow><mo>(</mo><mi>n</mi><mo>+</mo><mn>1</mn><mo>)</mo></mrow><mrow><mn>2</mn></mrow></msup></math></span> variables. When the highest weight is dominant integral, we find a span set for the corresponding finite-dimensional irreducible module. One can use the result to study tensor decomposition of finite-dimensional irreducible modules by solving certain first-order linear partial differential equations, and thereby obtain the corresponding physically interested Clebsch-Gordan coefficients and exact solutions of Knizhnik-Zamolodchikov equation in WZW model of conformal field theory. We also find an equation of counting the dimension of an irreducible <span><math><mi>o</mi><mo>(</mo><mn>2</mn><mi>n</mi><mo>+</mo><mn>3</mn><mo>)</mo></math></span>-module in terms of certain alternating sum of the dimensions of irreducible <span><math><mi>o</mi><mo>(</mo><mn>2</mn><mi>n</mi><mo>+</mo><mn>1</mn><mo>)</mo></math></span>-modules. In the case of the Steinberg modules, we obtain new combinatorial identities of classical type.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"681 ","pages":"Pages 62-106"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.04.044
Bojko Bakalov , Ju Wang
{"title":"Poisson pseudoalgebras","authors":"Bojko Bakalov , Ju Wang","doi":"10.1016/j.jalgebra.2025.04.044","DOIUrl":"10.1016/j.jalgebra.2025.04.044","url":null,"abstract":"<div><div>For any cocommutative Hopf algebra <em>H</em> and a left <em>H</em>-module <em>V</em>, we construct an operad <span><math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>H</mi></mrow><mrow><mi>c</mi><mi>l</mi></mrow></msubsup><mo>(</mo><mi>V</mi><mo>)</mo></math></span>, which in the special case when <em>H</em> is the algebra of polynomials in one variable reduces to the classical operad <span><math><msup><mrow><mi>P</mi></mrow><mrow><mi>c</mi><mi>l</mi></mrow></msup><mo>(</mo><mi>V</mi><mo>)</mo></math></span> of <span><span>[5]</span></span>. Morphisms from the Lie operad to <span><math><msup><mrow><mi>P</mi></mrow><mrow><mi>c</mi><mi>l</mi></mrow></msup><mo>(</mo><mi>V</mi><mo>)</mo></math></span> correspond to Poisson vertex algebra structures on <em>V</em>. Likewise, our operad <span><math><msubsup><mrow><mi>P</mi></mrow><mrow><mi>H</mi></mrow><mrow><mi>c</mi><mi>l</mi></mrow></msubsup><mo>(</mo><mi>V</mi><mo>)</mo></math></span> gives rise to the notion of a Poisson pseudoalgebra; thus extending the notion of a Lie pseudoalgebra from <span><span>[1]</span></span>. As a byproduct of our construction, we introduce two cohomology theories for Poisson pseudoalgebras, generalizing the variational and classical cohomology of Poisson vertex algebras.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"679 ","pages":"Pages 117-168"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144166622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.04.043
S. Azam
{"title":"Chevalley bases for elliptic extended affine Lie algebras of type A1","authors":"S. Azam","doi":"10.1016/j.jalgebra.2025.04.043","DOIUrl":"10.1016/j.jalgebra.2025.04.043","url":null,"abstract":"<div><div>We investigate Chevalley bases for extended affine Lie algebras of type <span><math><msub><mrow><mi>A</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>. The concept of integral structures for extended affine Lie algebras of rank greater than one has been successfully explored in recent years. However, for the rank one it has turned out that the situation becomes more delicate. In this work, we consider <span><math><msub><mrow><mi>A</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span>-type extended affine Lie algebras of nullity 2, known as elliptic extended affine Lie algebras. These Lie algebras are build using the Tits-Kantor-Koecher (TKK) construction by applying some specific Jordan algebras: the plus algebra of a quantum torus, the Hermitian Jordan algebra of the ring of Laurent polynomials equipped with an involution, and the Jordan algebra associated with a semilattice. By examining these ingredients we determine appropriate bases for null spaces of the corresponding elliptic extended affine Lie algebra leading to the establishment of Chevalley bases for these Lie algebras.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"680 ","pages":"Pages 148-173"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144168626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.05.008
Gregory Kendall
{"title":"The stable module category and model structures for hierarchically defined groups","authors":"Gregory Kendall","doi":"10.1016/j.jalgebra.2025.05.008","DOIUrl":"10.1016/j.jalgebra.2025.05.008","url":null,"abstract":"<div><div>In this work we construct a compactly generated tensor-triangulated stable category for a large class of infinite groups, including those in Kropholler's hierarchy <span><math><mrow><mi>LH</mi></mrow><mi>F</mi></math></span>. This can be constructed as the homotopy category of a certain model category structure, which we show is Quillen equivalent to several other model categories, including those constructed by Bravo, Gillespie, and Hovey in their work on stable module categories for general rings. We also investigate the compact objects in this category. In particular, we give a topological characterisation of those groups of finite global Gorenstein AC-projective dimension such that the trivial representation <span><math><mi>Z</mi></math></span> is compact.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"681 ","pages":"Pages 107-151"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.05.005
Francesca S. Benanti , Angela Valenti
{"title":"A characterization of varieties of algebras of proper central exponent greater than two","authors":"Francesca S. Benanti , Angela Valenti","doi":"10.1016/j.jalgebra.2025.05.005","DOIUrl":"10.1016/j.jalgebra.2025.05.005","url":null,"abstract":"<div><div>Let <em>F</em> be a field of characteristic zero and let <span><math><mi>V</mi></math></span> be a variety of associative <em>F</em>-algebras. In <span><span>[19]</span></span> Regev introduced a numerical sequence measuring the growth of the proper central polynomials of a generating algebra of <span><math><mi>V</mi></math></span>. Such sequence <span><math><msubsup><mrow><mi>c</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>δ</mi></mrow></msubsup><mo>(</mo><mi>V</mi><mo>)</mo><mo>,</mo><mspace></mspace><mi>n</mi><mo>≥</mo><mn>1</mn></math></span>, is called the sequence of proper central polynomials of <span><math><mi>V</mi></math></span> and in <span><span>[12]</span></span>, <span><span>[13]</span></span> the authors computed its exponential growth. This is an invariant of the variety. They also showed that <span><math><msubsup><mrow><mi>c</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>δ</mi></mrow></msubsup><mo>(</mo><mi>V</mi><mo>)</mo></math></span> either grows exponentially or is polynomially bounded.</div><div>The purpose of this paper is to characterize the varieties of associative algebras whose exponential growth of <span><math><msubsup><mrow><mi>c</mi></mrow><mrow><mi>n</mi></mrow><mrow><mi>δ</mi></mrow></msubsup><mo>(</mo><mi>V</mi><mo>)</mo></math></span> is greater than two. As a consequence, we find a characterization of the varieties whose corresponding exponential growth is equal to two.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"679 ","pages":"Pages 96-116"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144166642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.04.046
Alexandre Turull
{"title":"Linear characters for blocks with cyclic defect","authors":"Alexandre Turull","doi":"10.1016/j.jalgebra.2025.04.046","DOIUrl":"10.1016/j.jalgebra.2025.04.046","url":null,"abstract":"<div><div>We show that associated with each <em>p</em>-block <em>B</em> with non trivial cyclic defect group <em>D</em> of a finite group are two linear characters <span><math><msub><mrow><mi>α</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> of a cyclic group <em>E</em> of order <em>e</em>. Here <em>e</em> is the number of non exceptional irreducible characters that <em>B</em> has. The first character <span><math><msub><mrow><mi>α</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> describes the action of <em>E</em> on <em>D</em>. The second character <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> arises from certain field extensions. The order of <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> is the <em>p</em>-local Schur index of any exceptional <span><math><mi>χ</mi><mo>∈</mo><mi>Irr</mi><mo>(</mo><mi>B</mi><mo>)</mo></math></span>, giving an alternative description of this invariant to the one given by Benard <span><span>[1]</span></span>. From the relationship of <span><math><msub><mrow><mi>α</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> and <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> we give an alternative description to the one given by Nebe <span><span>[6]</span></span> of the invariant associated with each exceptional <span><math><mi>χ</mi><mo>∈</mo><mi>Irr</mi><mo>(</mo><mi>B</mi><mo>)</mo></math></span>.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"681 ","pages":"Pages 22-45"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.04.038
Ajneet Dhillon, Sayantan Roy-Chowdhury
{"title":"Semiorthogonal decompositions for generalised Severi-Brauer schemes","authors":"Ajneet Dhillon, Sayantan Roy-Chowdhury","doi":"10.1016/j.jalgebra.2025.04.038","DOIUrl":"10.1016/j.jalgebra.2025.04.038","url":null,"abstract":"<div><div>The purpose of this paper is to use conservative descent to study semiorthogonal decompositions for some homogeneous varieties over general bases. We produce a semiorthogonal decomposition for the bounded derived category of coherent sheaves on a generalised Severi-Brauer scheme. This extends known results for Severi-Brauer varieties and Grassmannians. We use our results to construct semiorthogonal decompositions for flag varieties over arbitrary bases. This generalises a result of Kapranov.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"680 ","pages":"Pages 70-95"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144168623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.05.007
Miyu Suzuki
{"title":"A reformulation of the conjecture of Prasad and Takloo-Bighash","authors":"Miyu Suzuki","doi":"10.1016/j.jalgebra.2025.05.007","DOIUrl":"10.1016/j.jalgebra.2025.05.007","url":null,"abstract":"<div><div>Prasad and Takloo-Bighash proposed a conjecture which predicts a necessary condition in terms of epsilon factors for representations of <span><math><msub><mrow><mi>GL</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>(</mo><mi>F</mi><mo>)</mo></math></span> and its inner forms to have linear periods. In this rather expository article, we reformulate their conjecture in the following form: The distinguished members in each generic <em>L</em>-packet <span><math><msub><mrow><mi>Π</mi></mrow><mrow><mi>ϕ</mi></mrow></msub></math></span> are determined by the characters of the component group <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>ϕ</mi></mrow></msub></math></span> and local epsilon factors. We follow Aubert et al. for the definitions of the <em>L</em>-packets and the component groups.</div><div>We observe that under some hypotheses, the reformulated conjecture follows from the conjectural multiplicity formula recently proposed by Chen Wan for general spherical varieties and the conjectural integral formula for epsilon factors which we propose in this article.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"680 ","pages":"Pages 174-204"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144168627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-26DOI: 10.1016/j.jalgebra.2025.05.012
Lothar Sebastian Krapp , Salma Kuhlmann , Michele Serra
{"title":"Generalised power series determined by linear recurrence relations","authors":"Lothar Sebastian Krapp , Salma Kuhlmann , Michele Serra","doi":"10.1016/j.jalgebra.2025.05.012","DOIUrl":"10.1016/j.jalgebra.2025.05.012","url":null,"abstract":"<div><div>In 1882, Kronecker established that a given univariate formal Laurent series over a field can be expressed as a fraction of two univariate polynomials if and only if the coefficients of the series satisfy a linear recurrence relation. We introduce the notion of <em>generalised</em> linear recurrence relations for power series with exponents in an arbitrary ordered abelian group, and generalise Kronecker's original result. In particular, we obtain criteria for determining whether a multivariate formal Laurent series lies in the fraction field of the corresponding polynomial ring. Moreover, we study distinguished algebraic substructures of a power series field, which are determined by generalised linear recurrence relations. In particular, we identify generalised linear recurrence relations that determine power series fields satisfying additional properties which are essential for the study of their automorphism groups.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"681 ","pages":"Pages 152-189"},"PeriodicalIF":0.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Journal of AlgebraPub Date : 2025-05-23DOI: 10.1016/j.jalgebra.2025.05.004
Melvyn B. Nathanson
{"title":"Addition theorems in partially ordered groups","authors":"Melvyn B. Nathanson","doi":"10.1016/j.jalgebra.2025.05.004","DOIUrl":"10.1016/j.jalgebra.2025.05.004","url":null,"abstract":"<div><div>Shnirel'man's inequality and Shnirel'man's basis theorem are fundamental results about sums of sets of positive integers in additive number theory. It is proved that these results are inherently order-theoretic and extend to partially ordered abelian and nonabelian groups. One abelian application is an addition theorem for sums of sets of <em>n</em>-dimensional lattice points.</div></div>","PeriodicalId":14888,"journal":{"name":"Journal of Algebra","volume":"681 ","pages":"Pages 46-61"},"PeriodicalIF":0.8,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144170368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}