SL$_{4}(\textbf{Z})$ is not purely matricial field

We prove that every non-zero finite dimensional unitary representation of $\mathrm{SL}_{4}(\mathbf{Z})$ contains a non-zero $\mathrm{SL}_{2}(\mathbf{Z})$-invariant vector. As a consequence, there is no sequence of finite-dimensional representations of $\mathrm{SL}_{4}(\mathbf{Z})$ that gives rise to...

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Main Authors: Magee, Michael, de la Salle, Mikael
Format: Article
Language:English
Published: Académie des sciences 2024-10-01
Series:Comptes Rendus. Mathématique
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Online Access:https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.617/
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author Magee, Michael
de la Salle, Mikael
author_facet Magee, Michael
de la Salle, Mikael
author_sort Magee, Michael
collection DOAJ
description We prove that every non-zero finite dimensional unitary representation of $\mathrm{SL}_{4}(\mathbf{Z})$ contains a non-zero $\mathrm{SL}_{2}(\mathbf{Z})$-invariant vector. As a consequence, there is no sequence of finite-dimensional representations of $\mathrm{SL}_{4}(\mathbf{Z})$ that gives rise to an embedding of its reduced $C^*$-algebra into an ultraproduct of matrix algebras.
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institution Kabale University
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publishDate 2024-10-01
publisher Académie des sciences
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series Comptes Rendus. Mathématique
spelling doaj-art-3bc6a356ac584cc3a9a3e5f1e1eb26b32025-02-07T11:22:49ZengAcadémie des sciencesComptes Rendus. Mathématique1778-35692024-10-01362G890391010.5802/crmath.61710.5802/crmath.617SL$_{4}(\textbf{Z})$ is not purely matricial fieldMagee, Michael0de la Salle, Mikael1Department of Mathematical Sciences, Durham University, Lower Mountjoy, DH1 3LE Durham, UK; IAS Princeton, School of Mathematics, 1 Einstein Drive, Princeton 08540, USAIAS Princeton, School of Mathematics, 1 Einstein Drive, Princeton 08540, USA; Institut Camille Jordan, CNRS, Université Lyon 1, FranceWe prove that every non-zero finite dimensional unitary representation of $\mathrm{SL}_{4}(\mathbf{Z})$ contains a non-zero $\mathrm{SL}_{2}(\mathbf{Z})$-invariant vector. As a consequence, there is no sequence of finite-dimensional representations of $\mathrm{SL}_{4}(\mathbf{Z})$ that gives rise to an embedding of its reduced $C^*$-algebra into an ultraproduct of matrix algebras.https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.617/Special linear groupsFinite dimensionnal unitary representationsPurely MF groupsMF $C^*$-algebra
spellingShingle Magee, Michael
de la Salle, Mikael
SL$_{4}(\textbf{Z})$ is not purely matricial field
Comptes Rendus. Mathématique
Special linear groups
Finite dimensionnal unitary representations
Purely MF groups
MF $C^*$-algebra
title SL$_{4}(\textbf{Z})$ is not purely matricial field
title_full SL$_{4}(\textbf{Z})$ is not purely matricial field
title_fullStr SL$_{4}(\textbf{Z})$ is not purely matricial field
title_full_unstemmed SL$_{4}(\textbf{Z})$ is not purely matricial field
title_short SL$_{4}(\textbf{Z})$ is not purely matricial field
title_sort sl 4 textbf z is not purely matricial field
topic Special linear groups
Finite dimensionnal unitary representations
Purely MF groups
MF $C^*$-algebra
url https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.617/
work_keys_str_mv AT mageemichael sl4textbfzisnotpurelymatricialfield
AT delasallemikael sl4textbfzisnotpurelymatricialfield