Universität Jena, Fakultät für Mathematik & Informatik, Lehrstuhl Algebra

Oberseminar Algebra/Zahlentheorie - Vorträge 2015


WS 2015/2016

Dienstag, den 15. Dezember 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Prof. Dr. Jan Schröer,   (University of Bonn)
"Convolution algebras and enveloping algebras"
Dienstag, den 8. Dezember 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Prof. David J. Green,   (Universität Jena)
"The quaternion group has ghost number three II"
Dienstag, den 1. Dezember 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Dr. Leo Margolis,   (Universität Stuttgart)
"Torsion subgroups in the unit group of integral group rings"
Dienstag, den 24. November 2015, in JENA, SR 3517, Ernst-Abbe-Platz 2
Gemeinsames Oberseminar mit dem Mathematischen Institut der Universität Halle-Wittenberg
14:15-15:15 Uhr
Prof. Yuanyang Zhou   (Central China Normal University)
"Extensions of Morita and Rickard equivalences"
15:45-16:45 Uhr
Dr. Imke Toborg   (Universität Halle)
"Tabor groups with finiteness conditions"
17:00-18:00 Uhr
Prof. Burkhard Külshammer   (Universität Jena)
"Anchors of irreducible characters"
Einladung/Programm
Dienstag, den 17. November 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Pierre Landrock,   (Universität Jena)
"Blocks with defect group C24 and one irreducible Brauer character"
Dienstag, den 10. November 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Prof. David J. Green,   (Universität Jena)
"The quaternion group has ghost number three"
Dienstag, den 3. November 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
René Reichenbach,   (Universität Jena)
"Blöcke mit Defektgruppen V4 × P"
Dienstag, den 27. Oktober 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
André Prater,   (Universität Jena)
"Die Puig-Untergruppe"
Dienstag, den 20. Oktober 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
PD Dr. Jürgen Müller,   (Universität Jena)
"On abelian p-groups of symmetries of Riemann surfaces"
Abstract:
The genus spectrum of a finite group G is the set of all g such that G acts faithfully on a compact Riemann surface of genus g. It is an open problem to find a general description of the genus spectra of the groups in interesting classes, such as the abelian p-groups. Motivated by the work of Talu (2011) for odd primes p, we develop a general combinatorial machinery, for arbitrary primes, to obtain a structured description of the so-called reduced genus spectra of abelian p-groups.
This is joint work with Siddhartha Sarkar.

SS 2015

Dienstag, den 07. Juli 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Dr. Elizaveta Vishnyakova,   (MPIM Bonn)
"Invariant commutative n-ary superalgebras via the derived bracket construction"
Abstract:
A commutative n-ary superalgebra is called invariant if its multiplication is invariant with respect to a non-degenerate skew-symmetric form. This class of superalgebras contains all Lie algebras with invariant non-degenerate symmetric form, its n-ary generalizations and all commutative algebras with invariant non-degenerate skew-symmetric form. The main observation here is that we can obtain all these algebras using a derived bracket approach from Poisson geometry. Our talk is devoted to a discussion of invariant commutative n-ary superalgebras and other applications of the derived bracket formalism.
Dienstag, den 30. Juni 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Seyed Reza Hosseini   (Universität Jena)
"tba"
Dienstag, den 23. Juni 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Dr. Lewis Topley,   (Padova)
"Small representations for reduced enveloping algebras"
Abstract:
Although the ordinary representation theory of Lie algebras is extremely well developed, progress has been much slower in the modular case. A breakthrough was made twenty years ago when Premet proved a long-standing conjecture bounding the dimensions of modules. His techniques led to the discovery of finite W-algebras, and the latter theory has recently culminated in another milestone, showing that the bound mentioned before is best possible. I shall review the development of this theory and discuss some very recent results of mine regarding the structure theory of certain modular finite W-algebras.
Dienstag, den 16. Juni 2015, in HALLE/Saale, SR 3, Georg-Cantor-Haus, Theodor-Lieser-Str. 5
Gemeinsames Oberseminar mit dem Mathematischen Institut der Universität Halle-Wittenberg
Einladung/Programm
Dienstag, den 09. Juni 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Benjamin Sambale   (Universität Jena)
"Centers of block algebras"
Dienstag, den 02. Juni 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Philipp Kutzner,   (Universität Jena)
"Die Anzahl nilpotenter Matrizen mit Koeffizienten in Fq"
Dienstag, den 26. Mai 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Dr. Pavel Tumarkin,   (Durham University)
"Cluster algebras of finite mutation type and Coxeter groups"
Dienstag, den 19. Mai 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Prof. Burkhard Külshammer,   (Universität Jena)
"tba"
Dienstag, den 12. Mai 2015, in JENA, SR 3517, Ernst-Abbe-Platz 2
Gemeinsames Oberseminar mit dem Mathematischen Institut der Universität Halle-Wittenberg
Einladung/Programm
14:15-15:15 Uhr
Benjamin Sambale   (Universität Jena)
"Broué's Conjecture for the sporadic groups"
Abstract: We prove the isotypy version of Broué's Abelian Defect Group Conjecture for the sporadic groups, their covers and automorphism groups. This has been done for the principal blocks by Rouquier and it remains to deal with the non-principal blocks.
15:45-16:45 Uhr
Carolina Vallejo Rodríguez   (Universitat de València)
Coprime action and Brauer characters
Abstract: Let A and G be finite groups. If A acts coprimely on G it is well-known that there is a natural correspondence between the irreducible A-invariant characters of G and the irreducible characters of CG(A), the fixed point subgroup of the action. In the modular case, no natural correspondence is known in general. Indeed, it is an open conjecture that the number of irreducible A-invariant Brauer characters of G coincides with the number of irreducible Brauer characters of CG(A. We reduce this conjecture to a question on finite simple groups. (Joint work with B. Späth).
17:00-18:00 Uhr
Sergey Shpectorov   (University of Birmingham)
"Fusion systems related to Lie type groups of rank 2"
Abstract: This will be report on a joint project with E. Henke concerning fusion systems on Sylow p-subgroups of groups of Lie type of rank 2 in characteristic p.
Dienstag, den 05. Mai 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Prof. Maxim Nazarov,   (University of York )
"Representations of Yangians via Howe duality"
Abstract:
Yangians and their twisted analogues first appeared as basic examples of affine quantum groups and affine symmetric spaces, and found numerous applications as Quantum Integrable Systems. More recently, they made a remarkable reappearance in the theory of finite W-algebras. Classification of the irreducible finite-dimensional representations of these Yangians has been known for a long time, but explicit realisations of these representatitions were not known except in special cases. In this talk, it will be explained how to realise all these representations as quotients in tensor products of "fundamental" representations, by using the theory of Mickelsson algebras along with the Howe duality.
Dienstag, den 21. April 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Andre Prater,   (Universität Jena)
"Involution models on orthogonal groups"
Abstract:
Julio Brau has started studying involution models on orthogonal groups over finite fields of odd characteristics. In his work he proved the existence of such involution models for degree 2 and conjectured that there would only be involution models iff the degree of the group is at most 4. This talk sums up the results of my Bachelor thesis, in which I proved the conjecture for degree 3. I will start with explaining the concept of involution models and look at some examples. Later I will show how to construct involution models for groups O(3, q) for odd prime powers q. This will involve constructing an involution model for PGL(2, q).
Dienstag, den 14. April 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Dr. Eugenio Giannelli,   (Universität Kaiserslautern)
"Relative projectivity for Specht and simple modules of the symmetric group"
Abstract:
In this talk, I will start by introducing the basic ideas in the representation theroy of symmetric groups. In the second part of the talk I will describe the concept of relative projectivity for Specht and simple modules. I will conclude by presenting some new results on the topic.

WS 2014/2015

Dienstag, den 10.Februar 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Prof. Alexander Stolin,   (Göteborg, Schweden)
"Classification of quantum groups"
Dienstag, den 3. Februar 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Christian Desczyk ,   (Universität zu Köln)
"PBW filtration: Feigin-Fourier-Littelmann modules via Hasse diagrams"
Abstract:
We study the PBW filtration on the irreducible highest weight representations of simple complex finite-dimensional Lie algebras. This filtration is induced by the standard degree filtration on the universal enveloping algebra. For certain rectangular weights we provide a new description of the associated graded module in terms of generators and relations. We also construct a basis parametrized by the integer points of a normal polytope. The main tool we use is the Hasse diagram defined via the standard partial order on the positive roots. As an application we conclude that all representations considered in this paper are Feigin-Fourier-Littelmann modules.
Dienstag, den 27. Januar 2015, 14:15 Uhr, SR 3517, Ernst-Abbe-Platz 2
Dr. Florian Eisele,   (Vrije Universiteit Brussel)
"Basic algebras of blocks over a p-adic ring"
Abstract: pdf-Datei
Dienstag, den 20. Januar 2015, in JENA, SR 3517, Ernst-Abbe-Platz 2
Gemeinsames Oberseminar mit dem Mathematischen Institut der Universität Halle-Wittenberg
Einladung/Programm
14:15-15:15 Uhr Fatma Altunbulak Aksu   (Çankaya-Universität, Ankara; z.Zt. Universität Jena)
"Extraspecial p-groups and ghost numbers of group algebras"
15:45-16:45 Uhr Rebecca Waldecker   (Universität Halle)
"M9-free groups"
17:00-18:00 Uhr Deniz Kus   (Universität Köln)
"The Feigin-Loktev conjecture and truncated Weyl modules"
Abstract:
In this talk we discuss the category of graded representations of (twisted) current algebras and prove a special case of a conjecture made by Feigin and Loktev on fusion products. This allows us to realize certain truncated Weyl modules as fusion products of irreducible finite-dimensional representations..


Autor: <Ines.Spilling (at) uni-jena.de>.
Zuletzt geändert am 09.09.16