{"title":"Twisted Representations of the Extended Heisenberg-Virasoro Vertex Operator Algebra","authors":"Hongyan Guo, Huaimin Li","doi":"10.1007/s10468-024-10270-0","DOIUrl":"10.1007/s10468-024-10270-0","url":null,"abstract":"<div><p>In this paper, we study simple weak and ordinary twisted modules of the extended Heisenberg-Virasoro vertex operator algebra <span>(V_{tilde{mathcal {L}}_{F}}(ell _{123},0))</span>. We first determine the full automorphism groups of <span>(V_{tilde{mathcal {L}}_{F}}(ell _{123},0))</span> for all <span>(ell _{1}, ell _{2},ell _{3},Fin {mathbb C})</span>. They are isomorphic to certain subgroups of the general linear group <span>(text {GL}_{2}({mathbb C}))</span>. Then for a family of finite order automorphisms <span>(sigma _{r_{1},r_{2}})</span> of <span>(V_{tilde{mathcal {L}}_{F}}(ell _{123},0))</span>, we show that weak <span>(sigma _{r_{1},r_{2}})</span>-twisted <span>(V_{tilde{mathcal {L}}_{F}}(ell _{123},0))</span>-modules are in one-to-one correspondence with restricted modules of certain Lie algebras of level <span>(ell _{123})</span>, where <span>(r_{1}, r_2in {mathbb N})</span>. By this identification and vertex algebra theory, we give complete lists of simple ordinary <span>(sigma _{r_{1},r_{2}})</span>-twisted modules over <span>(V_{tilde{mathcal {L}}_{F}}(ell _{123},0))</span>. The results depend on whether <i>F</i> or <span>(ell _{2})</span> is zero or not. Furthermore, simple weak <span>(sigma _{r_{1},r_{2}})</span>-twisted <span>(V_{tilde{mathcal {L}}_{F}}(ell _{123},0))</span>-modules are also investigated. For this, we introduce and study restricted modules (including Whittaker modules) of a new Lie algebra <span>(mathcal {L}_{r_{1},r_{2}})</span> which is related to the mirror Heisenberg-Virasoro algebra.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 3","pages":"1563 - 1580"},"PeriodicalIF":0.5,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140833522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Mukai Conjecture for Fano Quiver Moduli","authors":"Markus Reineke","doi":"10.1007/s10468-024-10268-8","DOIUrl":"10.1007/s10468-024-10268-8","url":null,"abstract":"<div><p>We verify the Mukai conjecture for Fano quiver moduli spaces associated to dimension vectors in the interior of the fundamental domain.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 4","pages":"1641 - 1644"},"PeriodicalIF":0.5,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140803540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Galleries for Root Subsystems","authors":"Vladimir Shchigolev","doi":"10.1007/s10468-024-10269-7","DOIUrl":"10.1007/s10468-024-10269-7","url":null,"abstract":"<div><p>We consider the operations of projection and lifting of Weyl chambers to and from a root subsystems of a finite roots system. Extending these operations to labeled galleries, we produce pairs of such galleries that satisfy some common wall crossing properties. These pairs give rise to certain morphisms in the category of Bott-Samelson varieties earlier considered by the author. We prove here that all these morphisms define embeddings of Bott-Samelson varieties (considered in the original interpretation based on compact Lie groups due to Raoul Bott and Hans Samelson) skew invariant with respect to the compact torus. We prove that those embeddings that come from projection and lifting preserve two natural orders on the set of the points fixed by the compact torus. We also consider the application of these embeddings to equivariant cohomology. The operations of projection and lifting can also be applied separately to each segment of a gallery. We describe conditions that allow us to glue together the galleries obtained this way.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 3","pages":"1537 - 1561"},"PeriodicalIF":0.5,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140660395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Decompositions of Infinite-Dimensional (A_{infty , infty }) Quiver Representations","authors":"Nathaniel Gallup, Stephen Sawin","doi":"10.1007/s10468-024-10267-9","DOIUrl":"10.1007/s10468-024-10267-9","url":null,"abstract":"<div><p>Gabriel’s Theorem states that the quivers which have finitely many isomorphism classes of indecomposable representations are exactly those with underlying graph one of the ADE Dynkin diagrams and that the indecomposables are in bijection with the positive roots of this graph. When the underlying graph is <span>(varvec{A_n})</span>, these indecomposable representations are thin (either 0 or 1 dimensional at every vertex) and in bijection with the connected subquivers. Using linear algebraic methods we show that every (possibly infinite-dimensional) representation of a quiver with underlying graph <span>(varvec{A_{infty , infty }})</span> is infinite Krull-Schmidt, i.e. a direct sum of indecomposables, as long as the arrows in the quiver eventually point outward. We furthermore prove that these indecomposable are again thin and in bijection with both the connected subquivers and the limits of the positive roots of <span>(varvec{A_{infty , infty }})</span> with respect to a certain uniform topology on the root space. Finally we give an example of an <span>(varvec{A_{infty , infty }})</span> quiver which is not infinite Krull-Schmidt and hence necessarily is not eventually-outward.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 2","pages":"1513 - 1535"},"PeriodicalIF":0.5,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10468-024-10267-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140626695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Recasting the Hazrat Conjecture: Relating Shift Equivalence to Graded Morita Equivalence","authors":"Gene Abrams, Efren Ruiz, Mark Tomforde","doi":"10.1007/s10468-024-10266-w","DOIUrl":"10.1007/s10468-024-10266-w","url":null,"abstract":"<div><p>Let <i>E</i> and <i>F</i> be finite graphs with no sinks, and <i>k</i> any field. We show that shift equivalence of the adjacency matrices <span>(A_E)</span> and <span>(A_F)</span>, together with an additional compatibility condition, implies that the Leavitt path algebras <span>(L_k(E))</span> and <span>(L_k(F))</span> are graded Morita equivalent. Along the way, we build a new type of <span>(L_k(E))</span>–<span>(L_k(F))</span>-bimodule (a <i>bridging bimodule</i>), which we use to establish the graded equivalence.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 2","pages":"1477 - 1511"},"PeriodicalIF":0.5,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140582917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Gelfand-Tsetlin Modules: Canonicity and Calculations","authors":"Turner Silverthorne, Ben Webster","doi":"10.1007/s10468-024-10264-y","DOIUrl":"10.1007/s10468-024-10264-y","url":null,"abstract":"<div><p>In this paper, we give a more down-to-earth introduction to the connection between Gelfand-Tsetlin modules over <span>(mathfrak {gl}_n)</span> and diagrammatic KLRW algebras and develop some of its consequences. In addition to a new proof of this description of the category Gelfand-Tsetlin modules appearing in earlier work, we show three new results of independent interest: (1) we show that every simple Gelfand-Tsetlin module is a canonical module in the sense of Early, Mazorchuk and Vishnyakova, and characterize when two maximal ideals have isomorphic canonical modules, (2) we show that the dimensions of Gelfand-Tsetlin weight spaces in simple modules can be computed using an appropriate modification of Leclerc’s algorithm for computing dual canonical bases, and (3) we construct a basis of the Verma modules of <span>(mathfrak {sl}_n)</span> which consists of generalized eigenvectors for the Gelfand-Tsetlin subalgebra. Furthermore, we present computations of multiplicities and Gelfand-Kirillov dimensions for all integral Gelfand-Tsetlin modules in ranks 3 and 4; unfortunately, for ranks <span>(>4)</span>, our computers are not adequate to perform these computations.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 2","pages":"1405 - 1455"},"PeriodicalIF":0.5,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140312674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Restricted Injective Dimensions over Cohen-Macaulay Rings","authors":"Michal Hrbek, Giovanna Le Gros","doi":"10.1007/s10468-024-10262-0","DOIUrl":"10.1007/s10468-024-10262-0","url":null,"abstract":"<div><p>We show that the small and large restricted injective dimensions coincide for Cohen-Macaulay rings of finite Krull dimension. Based on this, and inspired by the recent work of Sather-Wagstaff and Totushek, we suggest a new definition of Cohen-Macaulay Hom injective dimension. We show that the class of Cohen-Macaulay Hom injective modules is the right constituent of a perfect cotorsion pair. Our approach relies on tilting theory, and in particular, on the explicit construction of the tilting module inducing the minimal tilting class recently obtained in (Hrbek et al. 2022).</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 2","pages":"1373 - 1393"},"PeriodicalIF":0.5,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140168499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Érica Z. Fornaroli, Mykola Khrypchenko, Ednei A. Santulo Jr
{"title":"Commutativity Preservers of Incidence Algebras","authors":"Érica Z. Fornaroli, Mykola Khrypchenko, Ednei A. Santulo Jr","doi":"10.1007/s10468-024-10265-x","DOIUrl":"10.1007/s10468-024-10265-x","url":null,"abstract":"<div><p>Let <i>I</i>(<i>X</i>, <i>K</i>) be the incidence algebra of a finite connected poset <i>X</i> over a field <i>K</i> and <i>D</i>(<i>X</i>, <i>K</i>) its subalgebra consisting of diagonal elements. We describe the bijective linear maps <span>(varphi :I(X,K)rightarrow I(X,K))</span> that strongly preserve the commutativity and satisfy <span>(varphi (D(X,K))=D(X,K))</span>. We prove that such a map <span>(varphi )</span> is a composition of a commutativity preserver of shift type and a commutativity preserver associated to a quadruple <span>((theta ,sigma ,c,kappa ))</span> of simpler maps <span>(theta )</span>, <span>(sigma )</span>, <i>c</i> and a sequence <span>(kappa )</span> of elements of <i>K</i>.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 2","pages":"1457 - 1476"},"PeriodicalIF":0.5,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140168498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Criterion for Quasi-Heredity","authors":"Yuichiro Goto","doi":"10.1007/s10468-024-10263-z","DOIUrl":"10.1007/s10468-024-10263-z","url":null,"abstract":"<div><p>Dlab and Ringel showed that algebras being quasi-hereditary in all orders for indices of primitive idempotents becomes hereditary. So, we are interested in for which orders a given quasi-hereditary algebra is again quasi-hereditary. As a matter of fact, we consider permutations of indices, and if the algebra with permuted indices is quasi-hereditary, then we say that this permutation gives quasi-heredity. In this article, we give a criterion for adjacent transpositions giving quasi-heredity, in terms of homological conditions of standard or costandard modules over a given quasi-hereditary algebra.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 2","pages":"1395 - 1403"},"PeriodicalIF":0.5,"publicationDate":"2024-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140105213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Rota-Baxter Lie bialgebras, classical Yang-Baxter equations and special L-dendriform bialgebras","authors":"Chengming Bai, Li Guo, Guilai Liu, Tianshui Ma","doi":"10.1007/s10468-024-10261-1","DOIUrl":"10.1007/s10468-024-10261-1","url":null,"abstract":"<div><p>This paper extends the well-known fact that a Rota-Baxter operator of weight 0 on a Lie algebra induces a pre-Lie algebra, to the level of bialgebras. We first show that a nondegenerate symmetric bilinear form that is invariant on a Rota-Baxter Lie algebra of weight 0 gives such a form that is left-invariant on the induced pre-Lie algebra and thereby gives a special L-dendriform algebra. This fact is obtained as a special case of Rota-Baxter Lie algebras with an adjoint-admissible condition, for a representation of the Lie algebra to admit a representation of the Rota-Baxter Lie algebra on the dual space. This condition can also be naturally formulated for Manin triples of Rota-Baxter Lie algebras, which can in turn be characterized in terms of bialgebras, thereby extending the Manin triple approach to Lie bialgebras. In the case of weight 0, the resulting Rota-Baxter Lie bialgebras give rise to special L-dendriform bialgebras, lifting the aforementioned connection that a Rota-Baxter Lie algebra induces a pre-Lie algebra to the level of bialgebras. The relationship between these two classes of bialgebras is also studied in terms of the coboundary cases, classical Yang-Baxter equations and <span>(mathcal {O})</span>-operators.</p></div>","PeriodicalId":50825,"journal":{"name":"Algebras and Representation Theory","volume":"27 2","pages":"1347 - 1372"},"PeriodicalIF":0.5,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140004540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}