Generic stabilizers for simple algebraic groups acting on orthogonal and symplectic Grassmannians

We consider faithful actions of simple algebraic groups on self-dual irreducible modules and on the associated varieties of totally singular subspaces, under the assumption that the dimension of the group is at least as large as the dimension of the variety. We prove that in all but a finite list of...

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Main Author: Aluna Rizzoli
Format: Article
Language:English
Published: Cambridge University Press 2025-01-01
Series:Forum of Mathematics, Sigma
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Online Access:https://www.cambridge.org/core/product/identifier/S2050509424001543/type/journal_article
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author Aluna Rizzoli
author_facet Aluna Rizzoli
author_sort Aluna Rizzoli
collection DOAJ
description We consider faithful actions of simple algebraic groups on self-dual irreducible modules and on the associated varieties of totally singular subspaces, under the assumption that the dimension of the group is at least as large as the dimension of the variety. We prove that in all but a finite list of cases, there is a dense open subset where the stabilizer of any point is conjugate to a fixed subgroup, called the generic stabilizer. We use these results to determine whether there exists a dense orbit. This in turn lets us complete the answer to the problem of determining all pairs of maximal connected subgroups of a classical group with a dense double coset.
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institution Kabale University
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series Forum of Mathematics, Sigma
spelling doaj-art-4280282f5527458cbb4ff4438c1bd1a42025-01-24T05:20:20ZengCambridge University PressForum of Mathematics, Sigma2050-50942025-01-011310.1017/fms.2024.154Generic stabilizers for simple algebraic groups acting on orthogonal and symplectic GrassmanniansAluna Rizzoli0https://orcid.org/0000-0003-1501-3501King’s College London, Strand, London WC2R 2LS, UK;We consider faithful actions of simple algebraic groups on self-dual irreducible modules and on the associated varieties of totally singular subspaces, under the assumption that the dimension of the group is at least as large as the dimension of the variety. We prove that in all but a finite list of cases, there is a dense open subset where the stabilizer of any point is conjugate to a fixed subgroup, called the generic stabilizer. We use these results to determine whether there exists a dense orbit. This in turn lets us complete the answer to the problem of determining all pairs of maximal connected subgroups of a classical group with a dense double coset.https://www.cambridge.org/core/product/identifier/S2050509424001543/type/journal_article14L3014M15
spellingShingle Aluna Rizzoli
Generic stabilizers for simple algebraic groups acting on orthogonal and symplectic Grassmannians
Forum of Mathematics, Sigma
14L30
14M15
title Generic stabilizers for simple algebraic groups acting on orthogonal and symplectic Grassmannians
title_full Generic stabilizers for simple algebraic groups acting on orthogonal and symplectic Grassmannians
title_fullStr Generic stabilizers for simple algebraic groups acting on orthogonal and symplectic Grassmannians
title_full_unstemmed Generic stabilizers for simple algebraic groups acting on orthogonal and symplectic Grassmannians
title_short Generic stabilizers for simple algebraic groups acting on orthogonal and symplectic Grassmannians
title_sort generic stabilizers for simple algebraic groups acting on orthogonal and symplectic grassmannians
topic 14L30
14M15
url https://www.cambridge.org/core/product/identifier/S2050509424001543/type/journal_article
work_keys_str_mv AT alunarizzoli genericstabilizersforsimplealgebraicgroupsactingonorthogonalandsymplecticgrassmannians