AG Algebra, Geometrie und Computeralgebra

Guest Seminar Groups and Representations (AG Malle)

Winter Semester 2023/24

Organisers:   Jun.-Prof. Dr. Caroline Lassueur,  Prof. Dr. Gunter Malle


During the Winter Semester 2023/24 the seminar is essentially replaced by the meeting Representation Theory at the Villa Denis 2023


  • Friday,  6th of October
    • 09:30 - 10:15 Noelia Rizo: Minimal heights and defect groups with two character degrees
    • 10:20 - 10:50 Jonas Hetz: The values of unipotent characters at unipotent elements for groups of type E8
    • 11:20 - 12:00 Marie Roth: Character sheaves of the principal series restricted to a conjugacy class
    • 14:00 - 14:30: Sergio David Cia Luvecce: On a formula for the Lusztig induction over the unipotent representations of O_2^{\pm}(F_q)
    • 14:35 - 15:05 Laura Voggesberger: Maximal Subgroups of Connected Reductive Groups
    • 15:30 - 16:15 Jay Taylor: Real Elements in Finite Reductive Groups
  • Saturday,  7th of October
    • 09:30 - 10:15 Marc Cabanes: On the McKay Conjecture
    • 10:45 - 11:15 Linda Hoyer: Oddness of orthogonal determinants of even-dimensional Specht modules
    • 11:15 - 12:00 Eirini Chavli: The center of walled Brauer algebras

Frühere Semester

Organisers:   Jun.-Prof. Dr. Caroline Lassueur,  Prof. Dr. Gunter Malle

The talks take place in Room 48-436.

  • Thursday, 20th of April 2023:  No Seminar
  • Thursday, 27th of April 2023  
    • 17:00-17:50 :  Nadia Romero  [Universidad de GuanajuatoA semisimplicity criterion for Green biset functors, with one application
    • Abstract :  We will prove a criterion giving conditions for the category of modules over a Green biset functor to be semisimple. The criterion is not hard to prove and it is useful for applications. As an example, we will see that for any fields \(k\) and \(F\) of characteristic \(0\) and any finite group \(T\), the category of modules over the shifted Green biset functor \((kR_F)_T\) of \(F\)-linear representations, is semisimple. This is joint work with Serge Bouc.

  • Thursday, 4th of May 2023:
    • 17:00-17:50 :  Nicola Grittini [RPTU Kaiserslautern-Landau] Character degrees and characters values
    • Abstract: Character theory of finite groups is traditionally focused on the study of character degrees, since they are relatively easy to control and they can provide much information on group structure. The rest of the character table, on the other hand, is often overlooked, with few exceptions, as when rational-valued and real-valued characters are considered. Even in this case, however, one may ask if the characters having values in the fields \(\mathbb{Q}\) and \(\mathbb{R}\) are actually special, or if the theorems involving these characters are just special cases of some more general properties.
      In recent years, a more systematic research on character fields of values has begun, possibly as a consequence of the study on the so-called Galois-McKay conjecture. We will see some of the problems and recent results concerning characters (fields of) values, and we will talk about why they can be interesting and how they interact with known results on rational and real-valued characters.
  • Thursday, 11th of May 2023:
    • 17:00-17:50 :Andrew P. Turner  [University of Pennsylvania (UPENN)] F-Theory and Singular Elliptic Fibrations
    • Abstract : I will discuss a powerful geometric approach to string theory called F-theory, and its mathematical foundations. The primary objects of interest are singular elliptically fibered Calabi–Yau manifolds and their resolutions. I will introduce and discuss elliptic fibrations, as well as various associated quantities and techniques we are interested in, and will briefly allude to their physical significance. This talk is associated with an ongoing effort with Martin Bies and many others in the OSCAR community to create a system of tools within OSCAR for doing F-theory computations.
  • Thursday, 18th of May 2023: No Seminar (Christi Himmelfahrt)
  • Thursday, 25th of May 2023:
    • 17:00-17:50 : Jérémie Guilhot  [Université de Tours] Recognising Kazhdan-Lusztig cells using representations
    • Abstract : The aim of this talk is to show on various examples that one can recognize Kazhdan-Lusztig cells using representations of Hecke algebras. This idea is especially interesting in the case of affine Weyl groups where one can use representations that have a very nice combinatorial descriptions in terms of alcove paths. (Joint work with James Parkinson)
  • Thursday, 1st of June 2023:
    • 17:00-17:50 : Loïc Poulain d'Andecy   [Université de Reims Champagne Ardenne]  KLR-type presentation of affine Hecke algebras of classical types
    • Abstract: KLR algebras of type A have been a revolution in the representation theory of Hecke algebras of a type A flavour, thanks to the the Brundan-Kleshchev-Rouquier isomorphism relating them explicitly to the affine Hecke algebra of type A. KLR algebras of other types exist but are not related to affine Hecke algebras. In this talk I will present a generalisation of the KLR presentation for the affine Hecke algebra of type B/C (involving so-called orientifold KLR algebras) and I will discuss some applications. This talk is based on joint works with Salim Rostam and Ruari Walker.
  • Thursday, 8th of June 2023: No Seminar (Fronleichnam)
  • Thursday, 15th of June 2023:
    • 17:00-17:50 : Eda Kaja   [TU Darmstadt] Classification of non-solvable groups whose power graph is a cograph
    • Abstract : A recent, active branch of research in algebraic graph theory studies constructions of graphs whose vertex set is a group \(G\) and whose edges reflect the structure of \(G\) in some way. An important example of such a graph is the power graph of a group \(G\). Its vertices are the elements of \(G\) and there is an edge between distinct vertices \(x\) and \(y\) of \(G\) if and only if \(x\) is a power of \(y\) or \(y\) is a power of \(x\).

      We are interested in groups whose power graph is a cograph, i.e. it does not contain an induced subgraph isomorphic to a path of length four. We call such groups power-cograph groups. The problem of classifying power-cograph groups was posed by Cameron, Manna and Mehatari. They solved this problem for nilpotent groups and provided a classification in the case of finite simple groups relative to number theoretic problems. In this talk, I will present our classification of non-solvable power-cograph groups relative to the same number theoreticn problems. Additionally, our techniques allow us to precisely describe the structure of solvable power-cograph groups.
  • Thursday, 22nd of June 2023:
    • 17:00-17:50: Yasir Kızmaz   [Halle / Bilkent] A generalization of Alperin Fusion theorem and its applications
    • Abstract: Let $\F$ be a saturated fusion system on a finite \(p\)-group \(S\), and let \(P\) be a strongly $\F$-closed subgroup of \(S\). We define the concept ``$\F$-essential subgroups with respect to \(P\)" which are some proper subgroups of \(P\) satisfying some technical conditions, and show that an $\F$-isomorphism between subgroups of \(P\) can be factorised by some automorphisms of \(P\) and $\F$-essential subgroups with respect to \(P\). When \(P\) is taken to be equal to \(S\), the Alperin-Goldschmidt fusion theorem can be obtained as a special case. We also show that $P\unlhd \F$ if and only if there is no $\F$-essential subgroup with respect to \(P\). The following definition is made: A \(p\)-group \(P\) is \textit{strongly resistant} in saturated fusion systems if $P\unlhd \F$ whenever there is an over \(p\)-group \(S\) and a saturated fusion system $\F$ on \(S\) such that \(P\) is strongly $\F$-closed. We shall discuss and show the existence of several classes of \(p\)-groups which are strongly resistant.
  • Thursday, 29th of June 2023: No Seminar
  • Thursday, 6th of July 2023
    • 15:30-17:00: John Murray    [Maynooth University] Walking through the Alperin-McKay conjecture
    • Abstract: The Alperin-McKay conjecture (AMC) asserts that the number of height zero characters in a block of a finite group can be determined locally. AMC has been known to hold for symmetric groups for a long time. For 2-blocks, there is even an explicit bijection proving AMC. Seeking a certain local compatibility for all 2-blocks of fixed weight, I was led to formulate a very general conjecture about certain Littlewood-Richardson (L-R) coefficients. Each L-R coefficient gives the multiplicity of an irreducible character of a symmetric group in a character induced from a maximal Young subgroup. Each L-R coefficient equals the number of triangular configurations called honeycombs, which have given edges. In this talk I will describe a very simple model for honeycombs, which I call source-sink world. Then using ideas of Burgisser-Ikenmeyer, I will outline a possible proof for my conjecture which uses the notion of admissible walks on honeycombs.

  • Monday, 10th of July 2023
    • 15:30-17:00: Valentina Grazian  [Milano-Bicocca]   Fusion Systems: What is Known
    • Abstract:  Fusion systems made their first appearance in a 2006 paper by Puig and have since then been investigated by many researchers around the world. An important research direction involves the study of the behavior of exotic fusion systems (in particular at odd primes).
      In this talk we will present an overview of recent results concerning the classification of fusion systems on certain families of finite p-groups, highlighting the developments on the understanding of exotic fusion systems at odd primes.
  • Thursday, 13th of July 2023: No Seminar
  • Thursday, 20th of July 2023: No Seminar

Organisatoren: Jun.-Prof. Dr. Caroline Lassueur und Prof. Dr. Gunter Malle

Die Vorträge finden in Raum 48-436 statt.


  • Donnerstag, 27. Oktober 2022: Kein Seminar
    • Am Fr. 28.10. und Sa. 29.10. finden die Darstellungstheorietage 2022 in Kaiserslautern statt.
      • Fr. 14:00 - 14:50: Nicolas JaconCores and weights for Ariki-Koike algebras
      • Fr. 15:00 - 15:30: Lucas Ruhstorfer: The Alperin--McKay conjecture and groups of Lie type B and C
      • Fr. 16:10 - 17:00: Magdalena BoosFrom type A to all classical Lie types: Let's discuss Symmetric Representation Theory 
      • Fr. 17:10 - 17:40: Frank LübeckGreen functions and permutation characters 
      • Sa. 09:00 - 09:50: Benjamin SambaleSylow structure from the character table
      • Sa. 10:00 - 10:30: Damiano Rossi: Alternating sums for unipotent characters
      • Sa. 11:00 - 11:50: Thorsten HeidersdorfDeligne categories and complex representations of the finite linear group
      • Sa. 12:00 - 12:30: Alexander MillerFoulkes characters
  • Donnerstag, 3. November 2022:
    • 17:00-17:50 Uhr: Peter Symonds [University of Manchester]: The Module structure of a Group Action on a Ring 

      Consider a finite group \(G\) acting on a graded Noetherian \(k\)-algebra \(S\), for some field \(k\) of characteristic \(p\); for example \(S\) might be a polynomial ring. Regard \(S\) as a \(kG\)-module and consider the multiplicity of a particular indecomposable module as a summand in each degree. We show how this can be described in terms of homological algebra and how it is linked to the geometry of the group action on the spectrum of \(S\).

  • Donnerstag, 10. November 2023Kein Seminar
  • Donnerstag, 17. November 2022:
    • 17:00-17:50 Uhr: Patrick Serwene [TU Dresden]: Exotic and block-exotic fusion systems

      One of the main problems in the theory of fusion systems is the conjecture whether a fusion system arises in the form of a finite group if and only if it arises in the form of a \(p\)-block of a finite group. After discussing some applications, we present some advances tackling this conjecture. We introduce classes of fusion systems for which we know it holds true and also discuss the status for fusion systems of blocks of finite simple groups. We introduce a category, generalising block fusion systems, which plays an important role in our strategy to prove the conjecture.


  • Freitag, 18. November 2022:
    • Um 14:00 Uhr findet in Hörsaal 46-280 die Disputation von Birte Johansson statt. 
      Titel: The inductive McKay-Navarro condition for finite groups of Lie type
  • Donnerstag, 24. November 2022:
    • 17:00-17:50 Uhr: Margherita Piccolo [Heinrich Heine Universität Düsseldorf] : Representation growth of semisimple profinite groups

      A profinite group is called semisimple if it is the Cartesian product of finite simple groups. The representation growth of such groups can be studied looking at the distribution of irreducible representations by means of a zeta function, that is a Dirichlet generating function. Under certain restrictions, the representation growth is polynomial with a wide range of growth.
      Moreover, given a profinite group, it is generally a difficult question to determine if it is, in fact, isomorphic to a profinite completion of an abstract group. In this talk, I discuss a result of Kassabov and Nikolov which provides a criteria for a semisimple profinite group to be a profinite completion. Based on this, I report on my work which is aimed at constructing semisimple profinite groups with specified polynomial representation growth that
      arise as profinite completions of abstract groups (with the same representation growth).

  • Donnerstag, 1. Dezember 2022:
    • 17:00-17:50 Uhr: Kein Seminar
      Am Freitag, 2. Dezember 2022, um 14:00 Uhr findet in Hörsaal 48-208 die Disputation von Laura Voggesberger statt.
      Titel: Nilpotent Pieces in Lie Algebras of Exceptional Type in Bad Characteristic
  • Donnerstag, 8. Dezember 2022: Kein Seminar
    • Am Fr. 9.12. und Sa. 10.12.2022 findet die Nikolauskoferenz in Aachen statt.
  • Donnerstag, 15. Dezember 2022: Kein Seminar

  • Donnerstag, 5. Januar 2023:
    • 17:00-17:50 Uhr: Jason Semeraro[University of Leicester]: An Alperin-type conjecture for p-local compact groups

      If \(G\) is a finite group \(H\), the fusion system \(F\) of \(H\) is a category whose objects are subgroups of a (fixed) Sylow \(p\)-subgroup \(S\) and whose morphisms are \(H\) conjugation maps. An \(F\)-weight s a defect zero character of an \(F\)-automorphism group (taken up to conjugacy). Alperin's Weight Conjecture for the principal block \(B\) of \(H\) asserts that the number \(w(F)\) of \(F\)-weights is equal to the number of simple \(B\)-modules. If \(H=G(q)\) is a finite group of Lie type, then generically this number is \(|Irr(W)|\) where \(W\) is the Weyl group of G and is, in particular, independent of \(q\). This motivates the study of \(F\)-weights for the algebraic group \(G\) itself, where \(F\) is a \(p\)-local compact group, a fusion system on a discrete \(p\)-toral group \(S\). When \(F\) is connected - that is, when every \(p\)-element is conjugate to a toral element - we conjecture that \(w(F)=|Irr(W)\), and prove this holds (even for exotic examples) whenever \(v_p(|W|) < 2\) using the theory of blocks with cyclic defect group. Very recent additional work with Kessar and Malle establishes this conjecture in type \(A\), building on work of Oliver, Alperin, Fong and others. If time permits, I will also discuss a version of the Alperin-McKay conjecture in this context.

  • Donnerstag, 12. Januar 2023:
    • 17:00-17:50 Uhr: Abel Lacabanne [Université Clermont Auvergne]: Verma Howe duality and LKB representations of braid groups

      One of the most classical form of Howe duality relates the commuting action of two general linear Lie algebra on a polynomial ring. We will first discuss this duality in the specific case of \(\mathfrak{gl}_2\) and \(\mathfrak{gl}_n\). Specifically, we will explain how the polynomial ring decomposes as a direct sum of finite dimensional bimodules over \(\mathfrak{gl}_2 \times \mathfrak{gl}_n\). Then, we extend this duality in a context where Verma modules replace the finite dimensional representations of \(\mathfrak{gl}_2\). Surprisingly the dual picture leaves the realm of lowest and highest weight modules.
      As an application, we use a quantized version of this duality to study the irreducibility of the Lawrence--Krammer--Bigelow representations of braid groups.
      This is joint work with D. Tubbenhauer and P. Vaz.
  • Donnerstag, 19. Januar 2023:
    • 17:00-17:50 Uhr: Aluna Rizzoli  [Ecole Polytechnique Fédérale de Lausanne] : Isometry groups of norms

      For a closed subgroup \(H\) of \(\mathrm{GL}_n(\mathbb{R})\), define \(\hat{H}\) to be the largest subgroup of \(\mathrm{GL}_n(\mathbb{R})\) that has the same orbits as \(H\) on \(\mathbb{R}^n\). We prove that \(H\) is the full isometry group of a norm on \(\mathbb{R}^n\) if and only if \(\pm I\in H\) and \(H=\hat{H}\). Using this, we show that every compact Lie group with a central involution can be realised as the isometry group of a norm. We then study the relationship between \(H\) and \(\hat{H}\) for compact \(H\leq \mathrm{GL}_n(\mathbb{R})\), showing that, with specified exceptions, \(H\) and \(\hat{H}\) have the same connected component of the identity. This is joint work with Emmanuel Breuillard, Martin Liebeck and Assaf Naor. 
  • Donnerstag, 26. Januar 2023:
    • 17:00-17:50 Uhr: J. Miquel Martínez [Universitat de València]: Character correspondences and counting conjectures

      We discuss situations in which it is possible to find character correspondences for the McKay and Alperin—McKay conjectures with good properties. In particular, we explore how these correspondences can interact with character degrees and decomposition numbers. This is joint work with Damiano Rossi.
  • Donnerstag, 2. Februar 2023:
    • 17:00-17:50 Uhr: TBA
  • Donnerstag, 9. Februar 2023Kein Seminar


Organisatoren Jun.-Prof. Dr. Caroline Lassueur und Dr. Lucas Ruhstorfer

Die Vorträge finden in Raum 48-436 statt.


  • Donnerstag, 28. April 2022:
    • 17:00-17:50 Uhr: Georges Neaime (Universität Bielefeld & Ruhr-Universität Bochum): Towards the Linearity of Complex Braid Groups Abstract
  • Donnerstag, 2. Juni 2022:
    • 17:00-17:50 Uhr: Deniz Yilmaz (LAMFA, Université de Picardie Jules Verne): Functorial equivalence of blocks of finite groups Abstract
  • Donnerstag, 9. Juni 2022:
    • 17:00-17:50 Uhr: Nicola Grittini (Università Cattolica del Sacro Cuore, Brescia): On characters with small cyclotomic fields of values Abstract
  • Donnerstag, 23. Juni 2022:
    • 17:00-17:50 Uhr: Norman MacGregor (University of Birmingham): Tame blocks of finite groups Abstract
  • Dienstag, 19. Juli 2022 (48-562):
    • 8:30-9:10 Uhr Michael Geline (Northern Illinois University): Schur indices are controlled by local subgroups Abstract
    • 9:20-10:00 Uhr Emily Norton (University of Kent): Chunks of the decomposition matrix of a finite classical group that we can understand Abstract​​​​​​​

Organisatoren Jun.-Prof. Dr. Caroline Lassueur und Dr. Lucas Ruhstorfer

Dieses Semester findet das Seminar als hybrides Seminar zusammen mit dem Lehrstuhl für Algebra und Zahlentheorie der RWTH Aachen statt.

Die Vorträge finden entweder in Raum 48-582 oder online statt. Die Präsenzvorträge werden dabei auch gestreamt.


Termin: kein regelmäßiger Termin. Zur Anmeldung als externer Gast verwenden Sie bitte diesen Link.


  • Donnerstag, 13. Januar 2022 (Online):
    • 16:15-17:00 Uhr: Nicolas Jacon (Université de Reims Champagne-Ardenne): On the computation of the Mullineux involution for symmetric groups and Hecke algebras Abstract
    • 17:15-18:00 Uhr: William Murphy (City, University of London): The first Hochschild cohomology of blocks of finite group algebras Abstract
  • Donnerstag, 20. Januar 2022 (vor Ort):
  • Donnerstag, 27. Januar 2022 (Online):
    • 16:15-17:00 Uhr:  Carolina Vallejo (Universidad Autónoma de Madrid): Groups with a 2-generated Sylow 2-subgroup Abstract
    • 17:15-18:00 Uhr: Claudio Marchi (University of Manchester): Picard groups for blocks with normal defect group Abstract
  • Donnerstag, 10. Februar 2022 (vor Ort):
    • 17:00-18:00 Uhr: Julian Brough (Bergische Universität Wuppertal): Characters of normalisers of d-split Levi subgroups in Sp2n(q) Abstract


    Organisatoren Jun.-Prof. Dr. Caroline Lassueur, Dr. Lucas Ruhstorfer und M.Sc. Damiano Rossi (Bergische Universität Wuppertal)

    Dieses Semester findet das Seminar als virtuelles Seminar zusammen mit der Arbeitsgruppe Algebra und Zahlentheorie der Bergischen Universität Wuppertal statt.

    Termin: kein regelmäßiger Termin. Zur Anmeldung als externer Gast verwenden Sie bitte diesen Link.


    • Dienstag, 27. April 2021:
      • 16:00-16:45 Uhr: Eugenio Giannelli (Università degli Studi di Firenze): On a conjecture of Malle and Navarro  Abstract
      • 17:00-17:45 Uhr: Noelia Rizo (Universidad del País Vasco): On the trivial intersection block conjecture Abstract
    • Dienstag, 11. Mai 2021:
      • 16:00-16:45 Uhr: Virgilius-Aurelian Minuta (Babes-Bolyai University, Cluj-Napoca): Relations between module triples Abstract
      • 17:00-17:45 Uhr: Sofia Brenner (Friedrich-Schiller Universität Jena): On Socles of Centers of Group Algebras Abstract
    • Dienstag, 25. Mai 2021:
      • 16:00-16:45 Uhr: Scott Harper (University of Bristol): The spread of a finite group Abstract
      • 17:00-17:45 Uhr: Justin Lynd (University of Louisiana at Lafayette): Punctured groups for exotic fusion systems Abstract
    • Dienstag, 8. Juni 2021:
      • 16:00-16:45 Uhr: Michael Geline (Northern Illinois University): An overview of Knörr lattices for finite groups Abstract
      • 17:00-17:45 Uhr: Andrei Marcus (Babes-Bolyai University, Cluj, Napoca): Extending basic Morita equivalences Abstract
    • Dienstag, 29. Juni 2021 (organisiert von Prof. Dr. Max Horn):
      • 16:00-16:45 Uhr: Andrea Thevis (RWTH Aachen und Universität des Saarlands): Square-tiled surfaces, normal covers, and cylinder decompositions Abstract


      Organisatoren Jun.-Prof. Dr. Caroline Lassueur und  Dr. Lucas Ruhstorfer

      Termin: kein regelmäßiger Termin. Zur Anmeldung als externer Gast verwenden Sie bitte diesen Link.


      • Donnerstag, 14. Januar 2021:
        • 16:00-16:45 Uhr: Nadia Mazza (Lancaster, University): Endotrivial modules for finite groups of Lie type Abstract
        • 17:00-17:45 Uhr: Matthew Gelvin: Dade groups and relative syzygies for finite groups Abstract
      • Donnerstag, 28. Januar 2021:
        • 16:00-16:45 Uhr: Jay Taylor (University of Southern California):  Rationality Properties of Kawanaka Characters Abstract
        • 17:00-17:45 Uhr: Mandi A. Schaeffer Fry (MSU Denver): The inductive McKay-Navarro Conditions in Type C for the Prime 2 Abstract
      • Donnerstag, 4. Februar 2021:
        • 16:00-16:45 Uhr: Cesare Ardito (City, University of London): Classification of blocks and open conjectures Abstract
        • 17:00-17:45 Uhr: Patrick Serwene (City, University of London): Exotic and block-exotic fusion systems Abstract


        Organisatoren:Dr. Niamh Farrell, Jun.-Prof. Dr. Caroline Lassueur und  Lucas Ruhstorfer

        Termin: Donnerstags 17:00-18:00, Raum 48-436

        • Donnerstag, 31. Oktober 2019: Julian Brough (Bergische Universität Wuppertal)
          • Titel: A criterion for the inductive Alperin weight condition [Abstract]
        • Donnerstag, 7. November 2019: Paul Wedrich (MPI Bonn)
          • Titel: Quivers for SL(2) tilting modules [Abstract]
        • Donnerstag, 14. November 2019: kein Seminar
        • Donnerstag, 21. November 2019: Jens Eberhardt (UCLA, Bonn)
          • Titel: Motives in Geometric Representation Theory [Abstract]
        • Donnerstag, 28. November 2019: Ivo Dell'Ambrogio (Université de Lille)
          • Titel: The Green correspondence in algebra and topology [Abstract]
        • Donnerstag, 5. Dezember 2019: kein Seminar (Nikolaus Conference)
        • Donnerstag, 19. Dezember 2019: Ellen Henke (University of Aberdeen)
          • Titel: A generalisation of a theorem by Camina-Herzog [Abstract]
        • Donnerstag, 9. Januar 2020: kein Seminar
        • Donnerstag, 16. Januar 2020: kein Seminar (canceled)
        • Donnerstag, 23. Januar 2020: Jenny August (MPI Bonn)
          • Titel: Contraction Algebras in the Homological Minimal Model Programme [Abstract]
        • Donnerstag, 30. Januar2020: Vincent Beck (Université de Tours/ Université d'Orléans)
          • Titel: Cohomological computations for reflection groups and their braid groups and application to the determination of the finite subgroups of B/[P,P] [Abstract]
        • Donnerstag, 6. Februar 2020: Maike Gruchot (RWTH Aachen)
          • Titel: On a relative version of complete reducibility [Abstract]
        • Donnerstag, 13. Februar 2020: kein Seminar


        Organisatoren: Dr. Niamh Farrell  und Dr. Alessandro Paolini

        Termin: Donnerstags 17:00-18:00, Raum 48-436

        • Montag(!), 15. April 2019, 15:45 Uhr: Bernhard Böhmler [TU Kaiserslautern]
          • Titel: On a counter-example to a conjecture about Morita algebras [Abstract]
        • Donnerstag, 25. April 2019: Sophiane Yahiatene [Universität Bielefeld]
          • Titel: Hurwitz action and extended Weyl groups [Abstract]
        • Donnerstag, 2. Mai 2019: Jonas Hetz [Universität Stuttgart]
          • Titel: On the values of unipotent characters of finite groups of Lie type [Abstract]
        • Donnerstag, 9. Mai 2019: Martin Hofer [LMU München]
          • Titel: Construction of elliptic p-units [Abstract]
        • Donnerstag, 16. Mai 2019: Kein Seminar.
        • Donnerstag, 23. Mai 2019: Patrick Wegener [TU Kaiserslautern]
          • Titel: An invitation to Coxeter and Artin groups [Abstract]
        • Donnerstag, 30. Mai 2019: Kein Seminar (Christi Himmelfahrt).
        • Donnerstag, 6. Juni 2019: Thomas Weigel [Universita' di Milano-Bicocca] CANCELED!
          • Titel: tba
        • Donnerstag, 20. Juni 2019: Kein Seminar (Fronleichnam).
        • Montag, 24. Juni 2019: Michael Livesey [Universität Jena]
          • Titel: On Donovan's conjecture for abelian defect groups and strong Frobenius numbers [Abstract]
        • Donnerstag, 27. Juni 2019: Giovanni De Franceschi [University of Auckland]
          • Titel: Centralizers and conjugacy classes in finite classical groups [Abstract]
        • Donnerstag, 4. Juli 2019: Eugenio Giannelli [Università degli Studi di Firenze]
          • Titel: Character correspondences for symmetric and complex reflection groups [Abstract]
        • Montag, 8. Juli 2019, 15:30 (Raum 48-438): Shigeo Koshitani [Chiba University]
          • Title: Equivalences of blocks algebras
        • Donnerstag, 11. Juli 2019, 16:15-17:15 (!): Leo Margolis [Vrije Universiteit Brussel]
          • Titel: Blocks of defect 1 and units in integral group rings [Abstract]
        • Donnerstag, 18. Juli 2019: Vortrag im Oberseminar


        Organisatoren: Dr. Niamh Farrell  und Dr. Alessandro Paolini

        Termin: Donnerstags 17:15-18:15, Raum 48-436

        • Donnerstag, 25. Oktober 2018: Melissa Lee [Imperial College London],
          •  Titel: Bases of almost quasisimple groups and Pyber's conjecture [Abstract]
        • Donnerstag, 1. November 2018: Kein Seminar (Allerheiligen)
        • Donnerstag, 8. November 2018: Yann Palu [LAMFA, Amiens]
          • Titel: From cluster algebras to cluster categories [Abstract]
        • Donnerstag, 15. November 2018:Stacey Law [University of Cambridge]
          • Titel: Linear characters of Sylow subgroups of the symmetric group [Abstract]
        • Mittwoch(!), 21. November 2018, 17:15-18:15:Theodosios Douvropoulos [Institut de Recherche en Informatique Fontamentale]
          • Titel: Coxeter numbers: From fake degree palindromicity to the enumeration of reflection factorizations of regular elements [Abstract]
        • Donnerstag, 29. November 2018: Lleonard Rubio y Degrassi [University of Leicester]
          • Titel: On the Lie structure of $HH^1$ of tame blocks [Abstract]
        • Donnerstag, 6. Dezember 2018: Kein Seminar (Nikolaus Conference)
        • Donnerstag, 13. Dezember 2018: Ruwen Hollenbach [TU Kaiserslautern]
          • Titel: Quasi-Isolated Blocks of Finite Groups of Lie Type [Abstract]
        • Dienstag(!), 18. Dezember 2018, 17:15-18:15 (Raum: 48-208):Jesua Chavez [Institut de Mathématiques de Jussieu-Paris Rive Gauche]
          • Titel: Howe correspondence between Harish-Chandra series[Abstract]
        • Donnerstag, 3. Januar 2019: kein Seminar
        • Donnerstag, 17. Januar 2019: David Stewart [Newcastle]
          • Titel: Gröbner bases, smooth centralisers and the Lefschetz principle  [Abstract]
        • Donnerstag, 24. Januar 2019: Tung Le [University of Pretoria]
          • Titel: On Characters of a Sylow p-subgroup of a Chevalley group G(p^f)[Abstract]
        • Donnerstag, 31. Januar 2019:Simon Goodwin [University of Birmingham]
          • Titel: Representations of reduced enveloping algebras for gl_n and restricted Yangians[Abstract]
        • Donnerstag, 7. Februar 2019: kein Seminar
        • Donnerstag, 14. Februar 2019, 17:00 Uhr(!): Arezoo Aslizadeh [TU Kaiserslautern/ Shahid Beheshti University, Tehran]
          • Titel: The nilpotent multipliers of the direct sum of Lie algebras [Abstract]

        Organisatoren: Dr. Niamh Farrell and Dr. Alessandro Paolini

        • Donnerstag, 12. April 2018: Kein Seminar.
        • Donnerstag, 19. April 2018: Kein Seminar.
        • Donnerstag, 26. April 2018: Kein Seminar.
        • Donnerstag, 3. Mai 2018: Keivan Mallahi-Karai [Jacobs University, Bremen]
          • Titel: Kirillov's orbit method and the polynomiality of the essential dimension of p-groups
        • Montag, 7. Mai 2018: Thomas Gobet [University of Sydney]
          • Titel: Dual and classical generators of Artin groups of spherical type
        • Donnerstag, 17. Mai 2018: Zhicheng Feng [TU Kaiserslautern]
          • Titel: On the inductive blockwise Alperin weight condition for special linear and unitary groups
        • Donnerstag, 24. Mai 2018: Keine Seminar
        • Donnerstag, 31. Mai 2018: Kein Seminar (Fronleichnam)
        • Donnerstag, 7. Juni 2018: two seminars.
          • 16.30-17.30: İpek Tuvay [Mimar Sinan Fine Arts University, Istanbul]
            • Titel: Brauer indecomposability of Scott modules for the quadratic group Qd(p)
          • 17.30-18.30: Kivanc Ersoy [Freie Universität Berlin]
            • Titel: Groups with certain conditions on fixed points of automorphisms
        • Donnerstag, 14. Juni 2018: Iulian Simion [Babes-Bolyai University, Cluj]
          • Titel: Minimal realizations of finite groups of isometries
        • Donnerstag, 21. Juni 2018: Alex Malcolm [Heilbronn Institute for Mathematics, Bristol]
          • Titel: Strong reality in finite simple groups: on products of classes and characters
        • Donnerstag, 28. Juni 2018: Kein Seminar
        • Donnerstag, 05. Juli 2018: Kein Seminar
        • Donnerstag, 12. Juli 2018: Madeleine Whybrow [TU Kaiserslautern]
          • Titel: Constructing Majorana representations

        Organisatoren: Jun.-Prof. Dr. Caroline Lassueur and Dr. Alessandro Paolini

        • Donnerstag, 26. Oktober 2017: Andrew Mathas [University of Sydney]
          • Titel: Jantzen filtrations and graded Specht modules  
          • Donnerstag, 02. November 2017: Caroline Lassueur [TU Kaiserslautern]
            • Titel: Lifting Morita equivalences with an endo-permutation source
          • Donnerstag, 09. November 2017: Kein Seminar
          • Donnerstag, 16. November 2017: Olivier Dudas [Université Paris Diderot - Paris 7]
            • Titel: On the unitriangular shape of decomposition matrices for finite reductive groups
          • Donnerstag, 23. November 2017: Reda Chaneb [Université Paris Diderot - Paris 7]
            • Titel: Basic sets for unipotent blocks of finite reductive groups
          • Donnerstag, 7. December 2017,  Oberseminar Representation Theory : Emil Rotilio [TU Kaiserslautern]
            • Titel: Lie superalgebras in Physics  
          • Donnerstag, 14. December 2017: Stefano Sannella [University of Birmingham]       
            • Titel: Broué's conjecture and perverse equivalences                  
          • Donnerstag, 21. December 2017: Patrick Wegener [TU Kaiserslautern]
            • Titel: Hurwitz action in elliptic Weyl groups and coherent sheaves on a weighted projective line                  
          • Donnerstag, 11. Januar 2018: Kein Seminar.
          • Donnerstag, 18. Januar 2018: Florian Eisele [City, University of London]
            • Titel: A counterexample to the first Zassenhaus conjecture                  
          • Donnerstag, 25. Januar 2018: Petra Schwer [Karlsruher Institut für Technologie] 
            • Titel: Reflection length in affine Coxeter groups                
          • Donnerstag, 1. Februar 2018: Kein Seminar
          • Donnerstag, 8. Februar 2018: Kein Seminar

          Organisator: Dr. Alessandro Paolini

          • Donnerstag, 20. April 2017: Kein Seminar
          • Donnerstag, 27. April 2017: Kivanç Ersoy [TU Kaiserslautern]
            • Titel: Locally finite groups with small centralizers
          • Donnerstag, 4. Mai 2017: Emily Norton [Max Planck Institute Bonn]
            • Titel: The \mathfrak{sl}_\infty-crystal combinatorics of higher level Fock spaces
          • Donnerstag, 11. Mai 2017: Andreas Bächle [Vrije Universiteit Brussel]
            • Titel: Rationality of groups and centers of integral group rings
          • Donnerstag, 18. Mai 2017: Kein Seminar
          • Donnerstag, 25. Mai 2017: Kein Seminar
          • Donnerstag, 1. Juni 2017: Kein Seminar                          
          • Donnerstag, 08. Juni 2017: William Wong [TU Kaiserslautern]
            • Titel: A phenomenon in the representation of SL(2,q) in defining characteristics             
          • Donnerstag, 13. Juni 2017: Wolfgang Willems [Otto-von-Guericke-Universität Magdeburg]
            • Titel: On quasi-projective Brauer characters
          • Donnerstag, 22. Juni 2017: Baptiste Rognerud [IRMA, Straßburg]
            • Titel: A Morita theory for permutation modules                 
          • Donnerstag, 29. Juni 2017: Julian Külshammer [Universität Stuttgart]
            • Titel: Ringel duality as a special case of Koszul duality                
          • Donnerstag, 05. Juli 2017: Tung Le [University of Pretoria]
            • Titel: On the automorphisms of designs constructed from finite simple groups
          • Donnerstag, 13. Juli 2017: Kein Seminar ("Representation Theory in Kaiserslautern" Konferenz)
          • Donnerstag, 20. Juli 2017: Yujiao Sun [Universität Stuttgart]
            • Titel: Supercharacter theories for Sylow p-subgroups of finite exceptional groups of Lie type
          • *Freitag, 25. August 2017, 14:00-15:00*: Shigeo Koshitani [University of Chiba]
            • Titel: Brauer indecomposability of Alperin-Scott modules for finite non-abelian 2-groups

          Organisatoren: Dr. Julian Brough und Jun.-Prof. Dr. Caroline Lassueur

          • Donnerstag, 3. November 2016, : Yanjun Liu [TU Kaiserslautern]
            • Titel: Principal and defect-zero blocks of finite groups
          • Donnerstag, 24. November 2016, : Niamh Farrell [TU Kaiserslautern/City, University of London]
            • Titel: The rationality of blocks of quasi-simple finite groups
          • Donnerstag, 25. November 2016: Jesper Grodal [Københavns Universitet]
            • Titel: Endotrivial modules via homotopy theory
          • Donnerstag, 1. Dezember 2016: Emilio Pierro [Universität Bielefeld]
            • Titel: Quantities associated to the subgroup lattice
          • Donnerstag, 8. Dezember 2016: Kein Seminar: 9.-10. Dez. Nikolauskonferenz
          • Donnerstag, 15. Dezember 2016: Kein Seminar: Konferenz "Finite simple groups, their fusion systems and representations", EPFL
          • Donnerstag, 12. Januar 2017: Kein Seminar: 12.-14. Jan. Permutation Konferenz, Bielefeld University   
          • Donnerstag, 19. Januar 2017: Iris Köster [Universität Stuttgart]
            • Titel: Sylow Numbers in Character Tables and Integral Group Rings             
          • Donnerstag, 26. Januar 2017: Kein Seminar: 27.-28. Jan. Darstellungstheorietage 2016
          • Donnerstag, 6. Februar 2017: Magdalena Boos [RUHR- Universtität Bochum]
            • Titel: Using quiver representations to prove finiteness criteria                 
          • Donnerstag, 9. Februar 2017: Charles Eaton [University of Manchester]
            • Titel: Loewy lengths of blocks                
          • Donnerstag, 8. März 2017: Micheal Geline [Northern Illinois University]
            • Titel: Some quantitative and qualitative aspects of Knörr lattices

          Organisatoren: Dr. Thomas Gobet und Dr. Caroline Lassueur

          • Donnerstag, 21. April 2016, 15:30-16:30, Raum 48-582: Paul Balmer (UCLA, Bielefeld)
            • Titel: A quick tour of tensor triangular geometry
          • Donnerstag, 28. April 2016, 17:00-18:00: Jitendra Bajpai (MPI Bonn) - canceled
            • Titel: Introduction to the theory of hypergeometric groups
          • Donnerstag, 5. Mai 2016: no talk (Christi Himmelfahrt)
          • Mittwoch, 11. Mai 2016, 17:00-18:00, Raum 48-436: Jay Taylor (Padova)
            • Titel: Sums of Skew Characters of Symmetric Groups
          • Donnerstag, 12. May 2016, 17:00-18:00, Raum 48-436: Christopher Voll (Bielefeld)
            • Title: Representation growth of finitely generated nilpotent groups
          • Donnerstag, 19. Juni 2016: no talk because of workshop "Branching problems for reductive groups" at IML
          • Donnerstag, 26. Juni 2016: no talk because of Fronleichnam   
          • Donnerstag, 2. Juni 2016, 17:00-18:00, Raum 48-436: René Reichenbach (Jena)
            • Title: The Broué-Puig *-construction and some applications to 2-blocks            
          • Donnerstag, 26. Januar 2017: Kein Seminar: 27.-28. Jan. Darstellungstheorietage 2016
          • Donnerstag, 6. Februar 2017: Magdalena Boos [RUHR- Universtität Bochum]
            • Titel: Using quiver representations to prove finiteness criteria                 
          • Donnerstag, 9. Februar 2017: Charles Eaton [University of Manchester]
            • Titel: Loewy lengths of blocks                
          • Donnerstag, 8. März 2017: Micheal Geline [Northern Illinois University]
            • Titel: Some quantitative and qualitative aspects of Knörr lattices

          Organisatoren: Dr. Thomas Gobet und Dr. Caroline Lassueur

          • Donnerstag, 15. Oktober 2015, 16:00-17:00, Raum 48-436: Mikaël Cavallin [EPFL, Ecublens, CH]
            • Titel: Restriction of irreducibles and structure of Weyl modules
          • Donnerstag, 29. Oktober 2015: Philipp Perepelitsky [TU Kaiserslautern]
            • Titel: p-permutation equivalences between blocks of finite groups
          • Donnerstag, 5. November 2015: Benjamin Sambale [TU Kaiserslautern]
            • Titel: Broué's Conjecture for sporadic groups
          • Donnerstag, 12. November 2015: Neil Saunders [EPFL, Ecublens, CH]
            • Titel: Irreducible Components of Springer Fibres
          • Donnerstag, 19. November 2015: Thomas Gobet [TU Kaiserslautern]
            • Titel: On twisted filtrations on Soergel bimodules and linear Rouquier complexes
          • Mittwoch, 25. November 2015: Olivier Dudas [University Paris Diderot - Paris 7, FR]
            • Titel: On the unitriangular shape of decomposition matrices for finite reductive groups
          • Donnerstag, 26. November 2015: Chris Bowman [City University, London, UK]
            • Titel: The co-Pieri rule for Kronecker coefficients
          • Donnerstag, 3. Dezember 2015: Benedetta Lancellotti [Università degli Studi di Milano-Bicocca, IT]
            • Titel: Trivial source lattices and a strong form of McKay conjecture
          • Mittwoch, 9. Dezember 2015, 16:00-17:00, Raum 48-582: Patrick Wegener [Universität Bielefeld]
            • Titel: Hurwitz action in Coxeter Groups
          • Donnerstag, 17. Dezember 2015: Oberseminar Complex Reflection Groups
          • Donnerstag, 14. Januar 2016: Alessandro Paolini [University of Birmingham, UK]
            • Titel: A reduction of characters of Sylow p-subgroups of finite groups of Lie type
          • Donnerstag, 28. Januar 2016: Oliver Goodbourn [Ruhr-Universität Bochum]
            • Titel: Reductive pairs from representations of algebraic groups
          • Donnerstag, 4. Februar 2016: Julian Brough [TU Kaiserslautern]
            • Titel: Determining finite group structure from the size of the conjugacy classes
          • Donnerstag, 11. Februar 2016: John Murray [Maynooth University, IR]
            • Titel: Strong and weak reality and principal indecomposable modules in characteristic 2

          Organisatorinnen: Dr. habil. Britta Späth und Dr. Caroline Lassueur

          • Donnerstag, 23. April, 15:30-16:30, Raum 48-582: Ulrike Faltings [TU Kaiserslautern]
            • Titel: On the decomposition numbers of F_4(q) for q even
          • Donnerstag, 30. April, 15:30-16:30, Raum 48-582: Carolina Vallejo [Universitat de València]
            • Titel: Coprime action and Brauer characters
          • Dienstag, 12. Mai, 15:30-16:30, Raum 48-436: Danny Neftin [University of Michigan, Ann Arbor]
            • Titel: Monodromy groups of rational functions
          • Donnerstag, 21. Mai, 15:30-16:30, Raum 48-519: Vivien Ripoll [Universität Wien]
            • Titel: Coxeter elements in well-generated complex reflection groups
          • Donnerstag, 4. Juni: Kein Seminar (Fronleichnam)
          • Donnerstag, 15:30-16-30, 11. Juni: Amanda Schaeffer Fry [Metropolitan State University Denver]
            • Titel: Finite groups with an irreducible character of large degree
          • Donnerstag, 18. Juni, 17:00-18:00, Raum 48-436: Thomas Gerber [RWTH Aachen]
            • Titel: Weak Harish-Chandra theory for finite unitary groups
          • Donnerstag, 25. Juni, 15:30-16:15: Matthias Klupsch [RWTH Aachen]
            • Titel: Supercuspidal modules of finite reductive groups
          • Donnerstag, 16. Juli, 17:00-18:00, Seminarraum 48-436: Oksana Yakimova [Friedrich-Schiller-Universität Jena]
            • Titel: On symmetric invariants of semi-direct products
          • Donnerstag, 23. Juli: Kein Seminar

          Organisatorinnen: Dr. habil. Britta Späth und Dr. Caroline Lassueur

          • Donnerstag, 2. Oktober: Shigeo Koshitani [University of Chiba]
            • Titel: Remarks on the Loewy length of a block algebra
          • Donnerstag, 30. Oktober: Attila Maróti [TU Kaiserslautern]
            • Titel: Groups equal to a product of three conjugate proper subgroups
          • Donnerstag, 27. November: Imke Toborg [Universität Koblenz-Landau]
            • Titel: Local methods need some representation theory to prove Z_3^* results
          • Donnerstag, 18. Dezember: Sebastian Herpel [Ruhr-Universität Bochum]
            • Titel: Maximal subalgebras of Cartan Type in the exceptional Lie algebras
          • Donnerstag, 8. Januar: Tommy Hofmann [TU Kaiserslautern]
            • Titel: Integrality of Representations of Finite Groups
          • Donnerstag, 5. Februar, 17:00 Raum 48-436: Eirini Chavli [Université Paris Diderot - Paris 7]
            • Titel: The BMR freeness conjecture: the exceptional groups of rank 2         
          • Donnerstag, 19. Februar, 17:00 Raum 48-436: Barbara Baumeister [Universität Bielefeld]
            • Titel: Moufang twin buildings and Kac-Moody groups









          Organisatoren: Britta Späth und Jay Taylor

          • 24.04.2014, 17:00-18:00 (Room 48-436): Simon Schmider
            • Titel: On Auslander-Reiten components for Hecke algebras of type A
          • 08.05.2014, 17:00-18:00 (Room 48-436): Frank Himstedt [TU München]
            • Titel: On the decomposition numbers of the groups $\rm SO_7(q)$ and
              $\rm Sp_6(q)$
          • 22.05.2014, 17:00-18:00 (Room 48-436): Erwan Biland [Sherbrooke University, Kanada]
            • Titel: Stable equivalences related to the Z*p-theorem
          • 28.05.2014, 17:00-18:00 (Room 48-436): Pablo Luka
            • Titel: Vertex-bounded defects
          • 05.06.2014, 15:45-16:45 (Room 48-582): Eugenio Gianelli [Royal Holloway University of London]
            • Titel: On permutation modules and decomposition numbers of the symmetric group
          • 05.06.2014, 17:00-18:00 (Room 48-436): Hung P. Tong-Viet [Universität Bielefeld]
            • Titel: Some results on Brauer character degrees of finite groups
          • 12.06.2014, 17:00-18:00 (Room 48-436): Martino Garonzi [Università di Padova]
            • Titel: Factorizing a group with conjugate subgroups
          • 03.07.2014, 16:00-17:00 (Room 48-582): Giovanna Carnovale [Università di Padova]
            • Titel: Conjugacy classes in finite simple groups and pointed Hopf algebras        
          • 17.07.2014, 17:00-18:00 (Room 48-436): Martina Lanini [FAU Erlangen-Nürnberg]
            • Titel: Finite dimensional representations of rational Cherednik algebras









          Organisatorin: Britta Späth

          • 07.11.2013, 15:30-16:030 (Room 48-436): Philipp Perepelitsky
            • Titel: $p$-permutation equivalences between blocks of finite groups
          • 14.11.2013, 15:30-16:30 (Room 48-436): Iulian Simion
            • Titel: Refining the Bruhat decomposition
          • 21.11.2013: no talk
            • Baer Kolloqium (23.11.2013)
          • 28.11.2013, 15:30-16:30 (Room 48-436): Fuat Erdem
            • Titel: On the generating graph of a finite group
          • 05.12.2013: no talk
            • Titel: Darstellungstheorietage und Nikolauskonferenz
          • 12.12.2013, 16:00-17:00 (Room 48-436): Jürgen Müller
            • Titel: The Abelian Defect Group Conjecture for sporadic simple groups
          • 19.12.2013, 15:30-16:30 (Room 48-436): Olivier Dudas
            • Titel: Ordering conjugacy classes in Weyl groups
          • 09.01.2014, 15:30-16:30 (Room 48-436): Caroline Lassueur
            • Titel: The position of endo-$p$-permutation modules and relatives in the Auslander-Reiten quiver        
          • 16.01.2014, 17:00-18:00 (Room 48-436): Serge Bouc
            • Titel: The poset of posets
          • 23.01.2014, 15:30-16:30 (Room 48-436): Elisabeth Schulte
            • Titel: Alperin's Weight Conjecture - On Inductive Conditions for $G_2(q)$
          • 30.01.2014, 15:30-16:30 (Room 48-436): Burkhard Külshammer
            • Titel: Some questions in block theory
          • 10.02.2014, 15:30-16:30 (Room 48-436): Alessandro Paolini [University of Birmingham]
            • Titel: A Basis of the Gelfand-Graev Algebra of a Chevalley Group
          • 06.03.2014, 10:30-11:30 (Room 48-436): Michel Enguehard [Institut de Mathematique de Jussiue]
            • Titel: Towards a Jordan decomposition of blocks of finite reductive groups









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