Pub Date : 2026-04-01Epub Date: 2026-02-24DOI: 10.1016/j.jpaa.2026.108203
Victoria Gould , Ambroise Grau , Marianne Johnson , Mark Kambites
We consider the translational hull of an arbitrary subsemigroup I of an endomorphism monoid where A is a universal algebra. We give conditions for every bi-translation of I to be realised by transformations, or by endomorphisms, of A. We demonstrate that certain of these conditions are also sufficient to provide natural isomorphisms between the translational hull of I and the idealiser of I within , which in the case where I is an ideal is simply . We describe the connection between these conditions and work of Petrich and Gluskin in the context of densely embedded ideals. Where the conditions fail, we develop a methodology to extract information concerning from the translational hull of a quotient of I. We illustrate these concepts in detail in the cases where A is: a free algebra; an independence algebra; a finite symmetric group.
{"title":"Translational hulls of semigroups of endomorphisms of an algebra","authors":"Victoria Gould , Ambroise Grau , Marianne Johnson , Mark Kambites","doi":"10.1016/j.jpaa.2026.108203","DOIUrl":"10.1016/j.jpaa.2026.108203","url":null,"abstract":"<div><div>We consider the translational hull <span><math><mi>Ω</mi><mo>(</mo><mi>I</mi><mo>)</mo></math></span> of an arbitrary subsemigroup <em>I</em> of an endomorphism monoid <span><math><mi>End</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span> where <em>A</em> is a universal algebra. We give conditions for every bi-translation of <em>I</em> to be realised by transformations, or by endomorphisms, of <em>A</em>. We demonstrate that certain of these conditions are also sufficient to provide natural isomorphisms between the translational hull of <em>I</em> and the idealiser of <em>I</em> within <span><math><mi>End</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span>, which in the case where <em>I</em> is an ideal is simply <span><math><mi>End</mi><mo>(</mo><mi>A</mi><mo>)</mo></math></span>. We describe the connection between these conditions and work of Petrich and Gluskin in the context of densely embedded ideals. Where the conditions fail, we develop a methodology to extract information concerning <span><math><mi>Ω</mi><mo>(</mo><mi>I</mi><mo>)</mo></math></span> from the translational hull <span><math><mi>Ω</mi><mo>(</mo><mi>I</mi><mo>/</mo><mo>≈</mo><mo>)</mo></math></span> of a quotient <span><math><mi>I</mi><mo>/</mo><mo>≈</mo></math></span> of <em>I</em>. We illustrate these concepts in detail in the cases where <em>A</em> is: a free algebra; an independence algebra; a finite symmetric group.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 4","pages":"Article 108203"},"PeriodicalIF":0.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147388388","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}
Pub Date : 2026-03-01Epub Date: 2026-02-24DOI: 10.1016/j.jpaa.2026.108211
Martin Hyland , Ignacio López Franco , Christina Vasilakopoulou
This paper extends the theory of universal measuring comonoids to modules and comodules in braided monoidal categories. We generalise the universal measuring comodule , originally introduced for modules over -algebras when is a field, to arbitrary braided monoidal categories. In order to establish its existence, we prove a representability theorem for presheaves on opfibred categories and an adjoint functor theorem for opfibred functors. The global categories of modules and comodules, fibred and opfibred over monoids and comonoids respectively, are shown to exhibit an enrichment of modules in comodules. Additionally, we use our framework to study higher derivations of algebras and modules, defining along the way the non-commutative Hasse-Schmidt algebra.
{"title":"Measuring comodules and enrichment","authors":"Martin Hyland , Ignacio López Franco , Christina Vasilakopoulou","doi":"10.1016/j.jpaa.2026.108211","DOIUrl":"10.1016/j.jpaa.2026.108211","url":null,"abstract":"<div><div>This paper extends the theory of universal measuring comonoids to modules and comodules in braided monoidal categories. We generalise the universal measuring comodule <span><math><mi>Q</mi><mo>(</mo><mi>M</mi><mo>,</mo><mi>N</mi><mo>)</mo></math></span>, originally introduced for modules over <span><math><mi>k</mi></math></span>-algebras when <span><math><mi>k</mi></math></span> is a field, to arbitrary braided monoidal categories. In order to establish its existence, we prove a representability theorem for presheaves on opfibred categories and an adjoint functor theorem for opfibred functors. The global categories of modules and comodules, fibred and opfibred over monoids and comonoids respectively, are shown to exhibit an enrichment of modules in comodules. Additionally, we use our framework to study higher derivations of algebras and modules, defining along the way the non-commutative Hasse-Schmidt algebra.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108211"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422568","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}
Pub Date : 2026-03-01Epub Date: 2026-02-23DOI: 10.1016/j.jpaa.2026.108210
Monique Müller , Chelsea Walton
We use representations of braid groups of Coxeter types BC and D to produce invariants of representation categories of quasitriangular coideal subalgebras. Such categories form a prevalent class of braided module categories. This is analogous to how representations of braid groups of Coxeter type A produce invariants of representation categories of quasitriangular Hopf algebras, a prevalent class of braided monoidal categories. This work also includes concrete examples, and classification results for K-matrices of quasitriangular coideal subalgebras.
{"title":"Morita invariants of quasitriangular coideal subalgebras","authors":"Monique Müller , Chelsea Walton","doi":"10.1016/j.jpaa.2026.108210","DOIUrl":"10.1016/j.jpaa.2026.108210","url":null,"abstract":"<div><div>We use representations of braid groups of Coxeter types BC and D to produce invariants of representation categories of quasitriangular coideal subalgebras. Such categories form a prevalent class of braided module categories. This is analogous to how representations of braid groups of Coxeter type A produce invariants of representation categories of quasitriangular Hopf algebras, a prevalent class of braided monoidal categories. This work also includes concrete examples, and classification results for <em>K</em>-matrices of quasitriangular coideal subalgebras.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108210"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422569","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}
Pub Date : 2026-03-01Epub Date: 2026-02-23DOI: 10.1016/j.jpaa.2026.108202
Chengming Bai , Li Guo , Jianqi Liu , Xiaoyan Wang
Rota-Baxter operators, which can be viewed as the integral counterpart of derivations on algebras and operator forms of the classical Yang-Baxter equation, are defined and studied for vertex (operator) algebras. Examples of such operators are constructed for various vertex operator algebras. The closely related notion of dendriform algebras is also defined for vertex operator algebras. It is shown that the Rota-Baxter operators and dendriform structures give rise to new examples of vertex (Leibniz) algebras and vertex algebras without vacuum. The classical relations among dendriform algebras, associative algebras, Rota-Baxter algebras, and pre-Lie algebras are also extended to their vertex algebra analogs.
{"title":"On Rota-Baxter vertex operator algebras","authors":"Chengming Bai , Li Guo , Jianqi Liu , Xiaoyan Wang","doi":"10.1016/j.jpaa.2026.108202","DOIUrl":"10.1016/j.jpaa.2026.108202","url":null,"abstract":"<div><div>Rota-Baxter operators, which can be viewed as the integral counterpart of derivations on algebras and operator forms of the classical Yang-Baxter equation, are defined and studied for vertex (operator) algebras. Examples of such operators are constructed for various vertex operator algebras. The closely related notion of dendriform algebras is also defined for vertex operator algebras. It is shown that the Rota-Baxter operators and dendriform structures give rise to new examples of vertex (Leibniz) algebras and vertex algebras without vacuum. The classical relations among dendriform algebras, associative algebras, Rota-Baxter algebras, and pre-Lie algebras are also extended to their vertex algebra analogs.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108202"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422571","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}
Pub Date : 2026-03-01Epub Date: 2026-02-05DOI: 10.1016/j.jpaa.2026.108190
Gwyn Bellamy, Misha Feigin, Niall Hird
Originally motivated by connections to integrable systems, two natural subalgebras of the rational Cherednik algebra have been considered in the literature. The first is the subalgebra of all degree zero elements and the second is the Dunkl angular momentum subalgebra.
In this article, we study the ring-theoretic and homological properties of these algebras. Our approach is to realise them as rings of invariants under the action of certain reductive subgroups of . This allows us to describe their centres. Moreover, we show that they are Auslander–Gorenstein and Cohen–Macaulay and, at , give rise to prime PI-algebras whose PI-degree we compute.
Since the degree zero subalgebra can be realized as the ring of invariants for the maximal torus and the action of this torus on the rational Cherednik algebra is Hamiltonian, we also consider its (quantum) Hamiltonian reduction with respect to T. At , the quantum Hamiltonian reduction of the spherical subalgebra is a filtered quantization of the quotient of the minimal nilpotent orbit closure in by the reflection group W. At , we get a graded Poisson deformation of the symplectic singularity .
{"title":"Two invariant subalgebras of rational Cherednik algebras","authors":"Gwyn Bellamy, Misha Feigin, Niall Hird","doi":"10.1016/j.jpaa.2026.108190","DOIUrl":"10.1016/j.jpaa.2026.108190","url":null,"abstract":"<div><div>Originally motivated by connections to integrable systems, two natural subalgebras of the rational Cherednik algebra have been considered in the literature. The first is the subalgebra of all degree zero elements and the second is the Dunkl angular momentum subalgebra.</div><div>In this article, we study the ring-theoretic and homological properties of these algebras. Our approach is to realise them as rings of invariants under the action of certain reductive subgroups of <span><math><msub><mrow><mi>SL</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>. This allows us to describe their centres. Moreover, we show that they are Auslander–Gorenstein and Cohen–Macaulay and, at <span><math><mi>t</mi><mo>=</mo><mn>0</mn></math></span>, give rise to prime PI-algebras whose PI-degree we compute.</div><div>Since the degree zero subalgebra can be realized as the ring of invariants for the maximal torus <span><math><mi>T</mi><mo>⊂</mo><msub><mrow><mi>SL</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> and the action of this torus on the rational Cherednik algebra is Hamiltonian, we also consider its (quantum) Hamiltonian reduction with respect to T. At <span><math><mi>t</mi><mo>=</mo><mn>1</mn></math></span>, the quantum Hamiltonian reduction of the spherical subalgebra is a filtered quantization of the quotient of the minimal nilpotent orbit closure <span><math><msub><mrow><mover><mrow><mi>O</mi></mrow><mo>‾</mo></mover></mrow><mrow><mi>min</mi></mrow></msub></math></span> in <span><math><mrow><mi>gl</mi></mrow><mo>(</mo><mi>n</mi><mo>)</mo></math></span> by the reflection group <em>W</em>. At <span><math><mi>t</mi><mo>=</mo><mn>0</mn></math></span>, we get a graded Poisson deformation of the symplectic singularity <span><math><msub><mrow><mover><mrow><mi>O</mi></mrow><mo>‾</mo></mover></mrow><mrow><mi>min</mi></mrow></msub><mo>/</mo><mi>W</mi></math></span>.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108190"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146175450","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}
Pub Date : 2026-03-01Epub Date: 2026-02-05DOI: 10.1016/j.jpaa.2026.108188
S. Eswara Rao , Priyanshu Chakraborty
For any skew symmetric matrix over complex numbers, we introduce an EALA and it is called Skew Symmetric Extended Affine Lie Algebra (SSEALA). This way we get a large class of EALAs and most often they are non-isomorphic. In this paper we study irreducible integrable modules for SSEALA with finite dimensional weight spaces. We classify all such modules in the level zero case with non degenerate skew symmetric matrix.
{"title":"Skew Symmetric Extended Affine Lie algebras","authors":"S. Eswara Rao , Priyanshu Chakraborty","doi":"10.1016/j.jpaa.2026.108188","DOIUrl":"10.1016/j.jpaa.2026.108188","url":null,"abstract":"<div><div>For any skew symmetric matrix over complex numbers, we introduce an EALA and it is called Skew Symmetric Extended Affine Lie Algebra (SSEALA). This way we get a large class of EALAs and most often they are non-isomorphic. In this paper we study irreducible integrable modules for SSEALA with finite dimensional weight spaces. We classify all such modules in the level zero case with non degenerate skew symmetric matrix.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108188"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146154334","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}
Pub Date : 2026-03-01Epub Date: 2026-02-23DOI: 10.1016/j.jpaa.2026.108205
Lucrezia Bottegoni , Fabio Renda , Andrea Sciandra
Given a bialgebra H such that the associated trivial topological bialgebra admits a quasitriangular structure , one gets a distinguished element which is an infinitesimal -matrix, according to the definition given in [1]. In this paper we classify infinitesimal -matrices for some families of well-known Hopf algebras, among which are the generalized Kac–Paljutkin Hopf algebras , the Radford Hopf algebras , and the Hopf algebras .
{"title":"Infinitesimal R-matrices for some families of Hopf algebras","authors":"Lucrezia Bottegoni , Fabio Renda , Andrea Sciandra","doi":"10.1016/j.jpaa.2026.108205","DOIUrl":"10.1016/j.jpaa.2026.108205","url":null,"abstract":"<div><div>Given a bialgebra <em>H</em> such that the associated trivial topological bialgebra <span><math><mi>H</mi><mo>[</mo><mo>[</mo><mi>ħ</mi><mo>]</mo><mo>]</mo></math></span> admits a quasitriangular structure <span><math><mover><mrow><mi>R</mi></mrow><mrow><mo>˜</mo></mrow></mover><mo>=</mo><mi>R</mi><mo>(</mo><mn>1</mn><mo>⊗</mo><mn>1</mn><mo>+</mo><mi>ħ</mi><mi>χ</mi><mo>+</mo><mi>O</mi><mo>(</mo><msup><mrow><mi>ħ</mi></mrow><mrow><mn>2</mn></mrow></msup><mo>)</mo><mo>)</mo></math></span>, one gets a distinguished element <span><math><mi>χ</mi><mo>∈</mo><mi>H</mi><mo>⊗</mo><mi>H</mi></math></span> which is an infinitesimal <span><math><mi>R</mi></math></span>-matrix, according to the definition given in <span><span>[1]</span></span>. In this paper we classify infinitesimal <span><math><mi>R</mi></math></span>-matrices for some families of well-known Hopf algebras, among which are the generalized Kac–Paljutkin Hopf algebras <span><math><msub><mrow><mi>H</mi></mrow><mrow><mn>2</mn><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></msub></math></span>, the Radford Hopf algebras <span><math><msub><mrow><mi>H</mi></mrow><mrow><mo>(</mo><mi>r</mi><mo>,</mo><mi>n</mi><mo>,</mo><mi>q</mi><mo>)</mo></mrow></msub></math></span>, and the Hopf algebras <span><math><mi>E</mi><mo>(</mo><mi>n</mi><mo>)</mo></math></span>.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108205"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422585","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}
Pub Date : 2026-03-01Epub Date: 2026-02-24DOI: 10.1016/j.jpaa.2026.108204
Oskar Frost
Quasi-Lie bialgebras are natural extensions of Lie bialgebras, where the cobracket satisfies the co-Jacobi relation up to some natural obstruction controlled by a skew-symmetric 3-tensor ϕ. This structure was introduced by Drinfeld while studying deformation theory of universal enveloping algebras and has since seen many other applications in algebra and geometry. In this paper we study the derivation complex of strongly homotopy quasi-Lie bialgebra, both in the unwheeled (i.e. standard) and wheeled case, and compute its cohomology in terms of Kontsevich graph complexes.
{"title":"Graph complexes and deformation theories of the (wheeled) properads of quasi- and pseudo-Lie bialgebras","authors":"Oskar Frost","doi":"10.1016/j.jpaa.2026.108204","DOIUrl":"10.1016/j.jpaa.2026.108204","url":null,"abstract":"<div><div>Quasi-Lie bialgebras are natural extensions of Lie bialgebras, where the cobracket satisfies the co-Jacobi relation up to some natural obstruction controlled by a skew-symmetric 3-tensor <em>ϕ</em>. This structure was introduced by Drinfeld while studying deformation theory of universal enveloping algebras and has since seen many other applications in algebra and geometry. In this paper we study the derivation complex of strongly homotopy quasi-Lie bialgebra, both in the unwheeled (i.e. standard) and wheeled case, and compute its cohomology in terms of Kontsevich graph complexes.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108204"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422584","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}
Pub Date : 2026-03-01Epub Date: 2026-02-24DOI: 10.1016/j.jpaa.2026.108206
Eric M. Friedlander
We investigate infinite dimensional modules for a linear algebraic group over a field of positive characteristic p. For any subcoalgebra of the coordinate algebra of , we consider the abelian subcategory and the left exact functor that is right adjoint to the inclusion functor. The class of cofinite -modules is formulated using finite dimensional subcoalgebras of and the polynomial growth of various examples of cofinite modules is computed.
Infinite dimensional -modules of particular interest are those which are mock injective. Various examples of mock injective modules are investigated. For almost all linear algebraic groups , every mock injective -module J satisfies the condition that whenever for some finite dimensional sub-coalgebra .
{"title":"Infinite dimensional modules for linear algebraic groups","authors":"Eric M. Friedlander","doi":"10.1016/j.jpaa.2026.108206","DOIUrl":"10.1016/j.jpaa.2026.108206","url":null,"abstract":"<div><div>We investigate infinite dimensional modules for a linear algebraic group <span><math><mi>G</mi></math></span> over a field of positive characteristic <em>p</em>. For any subcoalgebra <span><math><mi>C</mi><mo>⊂</mo><mi>O</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span> of the coordinate algebra of <span><math><mi>G</mi></math></span>, we consider the abelian subcategory <span><math><mi>C</mi><mi>o</mi><mi>M</mi><mi>o</mi><mi>d</mi><mo>(</mo><mi>C</mi><mo>)</mo><mo>⊂</mo><mi>M</mi><mi>o</mi><mi>d</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span> and the left exact functor <span><math><msub><mrow><mo>(</mo><mo>−</mo><mo>)</mo></mrow><mrow><mi>C</mi></mrow></msub><mo>:</mo><mi>M</mi><mi>o</mi><mi>d</mi><mo>(</mo><mi>G</mi><mo>)</mo><mo>→</mo><mi>C</mi><mi>o</mi><mi>M</mi><mi>o</mi><mi>d</mi><mo>(</mo><mi>C</mi><mo>)</mo></math></span> that is right adjoint to the inclusion functor. The class of cofinite <span><math><mi>G</mi></math></span>-modules is formulated using finite dimensional subcoalgebras of <span><math><mi>O</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span> and the polynomial growth of various examples of cofinite modules is computed.</div><div>Infinite dimensional <span><math><mi>G</mi></math></span>-modules of particular interest are those which are mock injective. Various examples of mock injective modules are investigated. For almost all linear algebraic groups <span><math><mi>G</mi></math></span>, every mock injective <span><math><mi>G</mi></math></span>-module <em>J</em> satisfies the condition that <span><math><mi>H</mi><mi>o</mi><msub><mrow><mi>m</mi></mrow><mrow><mi>G</mi></mrow></msub><mo>(</mo><mi>J</mi><mo>,</mo><mi>M</mi><mo>)</mo><mo>=</mo><mn>0</mn></math></span> whenever <span><math><mi>M</mi><mo>=</mo><msub><mrow><mi>M</mi></mrow><mrow><mi>C</mi></mrow></msub></math></span> for some finite dimensional sub-coalgebra <span><math><mi>C</mi><mo>⊂</mo><mi>O</mi><mo>(</mo><mi>G</mi><mo>)</mo></math></span>.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108206"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422583","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}
Pub Date : 2026-03-01Epub Date: 2026-02-23DOI: 10.1016/j.jpaa.2026.108208
Yang He
In this paper, we showed that the strong Sarkisov program in dimension d can be derived from the termination of specific log flips in dimension . As a corollary, we prove that the strong Sarkisov program holds in dimension 4. Additionally, we prove the weak Sarkisov program with decreasing (augmented) Sarkisov degree. Finally, using the theory of syzygies of Mori fibre spaces, we obtain a directed diagram that encodes the information of the strong Sarkisov program.
{"title":"On the strong Sarkisov program","authors":"Yang He","doi":"10.1016/j.jpaa.2026.108208","DOIUrl":"10.1016/j.jpaa.2026.108208","url":null,"abstract":"<div><div>In this paper, we showed that the strong Sarkisov program in dimension <em>d</em> can be derived from the termination of specific log flips in dimension <span><math><mo>≤</mo><mi>d</mi><mo>−</mo><mn>1</mn></math></span>. As a corollary, we prove that the strong Sarkisov program holds in dimension 4. Additionally, we prove the weak Sarkisov program with decreasing (augmented) Sarkisov degree. Finally, using the theory of syzygies of Mori fibre spaces, we obtain a directed diagram that encodes the information of the strong Sarkisov program.</div></div>","PeriodicalId":54770,"journal":{"name":"Journal of Pure and Applied Algebra","volume":"230 3","pages":"Article 108208"},"PeriodicalIF":0.8,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147422553","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}