representation of the group theory

Group Representation

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Two representations are considered equivalent if they are similar . For example, performing similarity transformations of the above matrices by

This entry contributed by Todd Rowland

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Representation of a group

2020 Mathematics Subject Classification: Primary: 20B Secondary: 22F05 [ MSN ][ ZBL ]

A homomorphism of the group into the group of all invertible transformations of a set $V$.

A permutation representation is a homomorphism to the symmetric group $S_V$: a group action of $G$ on $V$: cf. Permutation group .

A representation $\rho$ of a group $G$ is called linear if $V$ is a vector space over a field $k$ and if the transformations $\rho(g)$, $g\in G$, are linear. Often, linear representations are, for shortness, simply termed representations (cf. Representation theory ). In the theory of representations of abstract groups the theory of finite-dimensional representations of finite groups is best developed (cf. Finite group, representation of a ; Representation of the symmetric groups ).

If $G$ is a topological group, then one considers continuous linear representations of $G$ on a topological vector space $V$ (cf. Continuous representation ; Representation of a topological group ). If $G$ is a Lie group and $V$ is a finite-dimensional space over $\mathbf R$ or $\mathbf C$, then a continuous linear representation is automatically real analytic. Analytic and differentiable representations of a Lie group are defined also in the infinite-dimensional case (cf. Analytic representation ; Infinite-dimensional representation ). To each differentiable representation $\rho$ of a Lie group $G$ corresponds some linear representation of its Lie algebra — the differential representation of $\rho$ (cf. Representation of a Lie algebra ). If $G$ is moreover connected, then its finite-dimensional representations are completely determined by their differentials. The most developed branch of the representation theory of topological groups is the theory of finite-dimensional linear representations of semi-simple Lie groups, which is often formulated in the language of Lie algebras (cf. Finite-dimensional representation ; Representation of the classical groups ; Cartan theorem on the highest weight vector), the representation theory of compact groups, and the theory of unitary representations (cf. Representation of a compact group ; Unitary representation ).

For algebraic groups one has the theory of rational representations (cf. Rational representation ), which is in many aspects analogous to the theory of finite-dimensional representations of Lie groups.

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JOURNAL OF THE AMS

Representation Theory

Published by the American Mathematical Society since 1997, this electronic-only journal is devoted to research in representation theory and seeks to maintain a high standard for exposition as well as for mathematical content. All articles are freely available to all readers and with no publishing fees for authors.

ISSN 1088-4165

The 2020 MCQ for Representation Theory is 0.71 . What is MCQ? The Mathematical Citation Quotient (MCQ) measures journal impact by looking at citations over a five-year period. Subscribers to MathSciNet may click through for more detailed information.

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On input and Langlands parameters for epipelagic representations HTML articles powered by AMS MathViewer

  • Anne-Marie Aubert , Paul Baum , Roger Plymen , and Maarten Solleveld , Depth and the local Langlands correspondence , Arbeitstagung Bonn 2013, Progr. Math., vol. 319, Birkhäuser/Springer, Cham, 2016, pp. 17–41. MR 3618046 , DOI 10.1007/978-3-319-43648-7_{2}
  • Anne-Marie Aubert , Paul Baum , Roger Plymen , and Maarten Solleveld , The local Langlands correspondence for inner forms of $\mathrm {SL}_n$ , Res. Math. Sci. 3 (2016), Paper No. 32, 34. MR 3579297 , DOI 10.1186/s40687-016-0079-4
  • Moshe Adrian , The Langlands parameter of a simple supercuspidal representation: odd orthogonal groups , J. Ramanujan Math. Soc. 31 (2016), no. 2, 195–214. MR 3518182
  • Moshe Adrian , Guy Henniart , Eyal Kaplan , and Masao Oi , Simple supercuspidal L-packets of split special orthogonal groups over dyadic fields , arXiv: 2305.09076 (2023).
  • Moshe Adrian and Eyal Kaplan , The Langlands parameter of a simple supercuspidal representation: symplectic groups , Ramanujan J. 50 (2019), no. 3, 589–619. MR 4031300 , DOI 10.1007/s11139-018-0060-5
  • Moshe Adrian and Eyal Kaplan , On the Langlands parameter of a simple supercuspidal representation: even orthogonal groups , Israel J. Math. 246 (2021), no. 1, 459–485. MR 4358290 , DOI 10.1007/s11856-021-2259-1
  • Anne-Marie Aubert , Sergio Mendes , Roger Plymen , and Maarten Solleveld , On $L$-packets and depth for $\textrm {SL}_2(K)$ and its inner form , Int. J. Number Theory 13 (2017), no. 10, 2545–2568. MR 3713091 , DOI 10.1142/S1793042117501421
  • James Arthur , The endoscopic classification of representations , American Mathematical Society Colloquium Publications, vol. 61, American Mathematical Society, Providence, RI, 2013. Orthogonal and symplectic groups. MR 3135650 , DOI 10.1090/coll/061
  • Anne-Marie Aubert and Yujie Xu , The explicit local Langlands correspondence for $G_2$ , arXiv: 2208.12391v2 (2022).
  • Colin J. Bushnell and Guy Henniart , The local Langlands conjecture for $\rm GL(2)$ , Grundlehren der mathematischen Wissenschaften [Fundamental Principles of Mathematical Sciences], vol. 335, Springer-Verlag, Berlin, 2006. MR 2234120 , DOI 10.1007/3-540-31511-X
  • Roger W. Carter , Simple groups of Lie type , Wiley Classics Library, John Wiley & Sons, Inc., New York, 1989. Reprint of the 1972 original; A Wiley-Interscience Publication. MR 1013112
  • Jessica Fintzen , On the Moy-Prasad filtration , J. Eur. Math. Soc. (JEMS) 23 (2021), no. 12, 4009–4063. MR 4321207 , DOI 10.4171/jems/1098
  • Jessica Fintzen , Types for tame $p$-adic groups , Ann. of Math. (2) 193 (2021), no. 1, 303–346. MR 4199732 , DOI 10.4007/annals.2021.193.1.4
  • Benedict H. Gross and Mark Reeder , Arithmetic invariants of discrete Langlands parameters , Duke Math. J. 154 (2010), no. 3, 431–508. MR 2730575 , DOI 10.1215/00127094-2010-043
  • Wee Teck Gan and Gordan Savin , The local Langlands conjecture for $G_2$ , Forum Math. Pi 11 (2023), Paper No. e28, 42. MR 4658199 , DOI 10.1017/fmp.2023.27
  • Guy Henniart , Une preuve simple des conjectures de Langlands pour $\textrm {GL}(n)$ sur un corps $p$-adique , Invent. Math. 139 (2000), no. 2, 439–455 (French, with English summary). MR 1738446 , DOI 10.1007/s002220050012
  • Kaoru Hiraga , Atsushi Ichino , and Tamotsu Ikeda , Formal degrees and adjoint $\gamma$-factors , J. Amer. Math. Soc. 21 (2008), no. 1 , 283–304. MR 2350057 , DOI 10.1090/S0894-0347-07-00567-X
  • Guy Henniart and Masao Oi , Simple supercuspidal $L$-packets of symplectic groups over dyadic fields , arXiv: 2207.12985v1 (2022).
  • Kaoru Hiraga and Hiroshi Saito , On $L$-packets for inner forms of $SL_n$ , Mem. Amer. Math. Soc. 215 (2012), no. 1013, vi+97. MR 2918491 , DOI 10.1090/S0065-9266-2011-00642-8
  • Michael Harris and Richard Taylor , The geometry and cohomology of some simple Shimura varieties , Annals of Mathematics Studies, vol. 151, Princeton University Press, Princeton, NJ, 2001. With an appendix by Vladimir G. Berkovich. MR 1876802
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  • Beth Romano , On the local Langlands correspondence: New examples from the epipelagic zone , ProQuest LLC, Ann Arbor, MI, 2016. Thesis (Ph.D.)–Boston College. MR 3517860
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  • Mark Reeder and Jiu-Kang Yu , Epipelagic representations and invariant theory , J. Amer. Math. Soc. 27 (2014), no. 2, 437–477. MR 3164986 , DOI 10.1090/S0894-0347-2013-00780-8
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  • Retrieve articles in Representation Theory of the American Mathematical Society with MSC (2020): 22E50 , 11S37
  • Beth Romano
  • Affiliation: Department of Mathematics, King’s College London, WC2R 2LS, United Kingdom
  • MR Author ID: 1229203
  • Email: [email protected]
  • Received by editor(s): March 18, 2023
  • Received by editor(s) in revised form: September 29, 2023, and December 5, 2023
  • Published electronically: February 12, 2024
  • © Copyright 2024 Copyright by the Authors
  • Journal: Represent. Theory 28 (2024), 90-111
  • DOI: https://doi.org/10.1090/ert/668
  • MathSciNet review: 4704423

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Title: hilbert series of representations of categories of $g$-sets.

Abstract: Let $G$ be a finite group. A contravariant functor from the category of finite free $G$-sets to vector spaces has an associated Hilbert series, which records the underlying sequence of $G^n$ representations, $n \in \mathbb N$. We prove that this Hilbert series is rational with denominator given by linear polynomials with coefficients in the field generated by the character table of $G$.

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