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Abstracts for MPI-Oberseminar

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Envelopes of holomorphy and holomorphic discs

Posted in
Speaker: 
Burglind Juhl-Jöricke
Affiliation: 
IHES
Date: 
Thu, 2011-04-28 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

Extension of analytic functions of one variable led to the notion of
Riemann surfaces and has applications to many branches of mathematics.
After a brief recollection I will focus on the effect in several
complex variables which made the multi-dimensional theory
geometric from the beginning and led to the notion of Stein manifolds
and envelopes of holomorphy.
I will describe a new construction of envelopes of holomorphy of
domains in terms of equivalence classes of analytic discs.
The construction is purely geometric and does not refer to the

A mixture of the tensor algebra and the infinite symmetric group and its application to the Schur--Weyl duality

Posted in
Speaker: 
Minoru Itoh
Affiliation: 
Kagoshima U/MPI
Date: 
Thu, 2011-05-05 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

We introduce a new algebra, which can be regarded as a mixture of the
tensor algebra and the infinite symmetric group.  As basic operators  on
this algebra, we can consider "multiplications" by vectors and
"derivations" by convectors.  These two types of operators satisfy an
analogue of the canonical commutation relations, and we can regard the
operator algebra generated by these as an analogue of the Weyl algebra  and
the Clifford algebra.  These algebras have applications to  noncommutative

Geometric construction of semicanonical bases and crystals of (affine) Lie algebras via quivers and Higgs bundles

Posted in
Speaker: 
Guillaume Pouchin
Affiliation: 
U Paris 6/MPI
Date: 
Thu, 2011-05-12 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

In this talk I will present the construction of enveloping Lie algebras via constructible fonctions on a stack of representation of a quiver (by Lusztig), as well as the geometric construction of the crystal (by Kashiwara-Saito).
I will then present how this techniques can be translated in the framework of Higgs bundles on a curve, in order to obtain loop Lie algebras.
 

On parametrization of phase spaces of Isomonodromic Deformations equations

Posted in
Speaker: 
M. Babich
Affiliation: 
Steklov Inst./MPI
Date: 
Thu, 2011-05-19 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

The isomonodromic deformation equations, which form the main stream of the evolution of the modern theory of special functions, may be associated with some algebraic Hamiltonian system. The Hamiltonian system is defined on the space that is the symplectic quotient of the product of the several coadjoint orbits. These spaces are the subject of our investigations.

The Busemann-Petty problem: generalizations and modifications

Posted in
Speaker: 
Alexander Koldobsky
Affiliation: 
U of Missouri, Columbia/MPI
Date: 
Thu, 2011-05-26 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

The Busemann-Petty asks whether symmetric convex bodies in R^n with smaller (n-1)-dimensional volume of all central hyperplane sections necessarily have smaller n-dimensional volume. The solution
was completed at the end of the 90's, and the answer is affirmative only in dimensions n\le 4. In this talk we present an overview of the solution, generalizations and applications.

 

Polygons in Euclidean Buildings of rank 2

Posted in
Speaker: 
Carlos Ramos-Cuevas
Affiliation: 
MPI
Date: 
Thu, 2011-06-09 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

Let X be a symmetric space of noncompact type (e.g. SL(n)/SO(n)) or a thick Euclidean bulding. We will discuss following geometric question: which are the possible side lengths of polygons in X?
The full invariant of an oriented geodesic segment in a symmetric space X=G/K modulo the action of G is a vector in \R^{rank(X)}. Thus in our context the appropriate notion of length is given by this vector. The same notion of vector valued length can be defined for Euclidean buildings.

Frobenius morphisms and derived categories on 2-dimensional toric stacks

Posted in
Speaker: 
R. Ohkawa
Affiliation: 
z.Z. MPI
Date: 
Thu, 2011-06-16 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

On standard modules of affine Hecke algebras of classical types

Posted in
Speaker: 
Syuchan Kato
Affiliation: 
U. of Tokyo
Date: 
Thu, 2011-07-07 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

Affine Hecke algebras are algebras defined as a deformation of affine Weyl
groups. Though it does not have equivalent representation theory as that of
affine Weyl groups, it inherits many structures from the counter-part of
affine Weyl groups.

In this talk, I will explain how the Specht construction (a classical
famous realization of irreducible representations of symmetric groups) fit
into the representation theory of affine Hecke algebras of classical types,
in a way it gives "standard modules" in some sense. This view point has

A p-adic approach to automorphic forms on Shimura curves. Computation and applications

Posted in
Speaker: 
Marc Masdeu
Affiliation: 
McGill U, Montreal/MPI
Date: 
Thu, 2011-07-14 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

The explicit computation of spaces of automorphic forms is a
very active and useful area of research in computational number
theory. Several authors have described algorithms to compute these
Hecke modules: to name a few, John Voight, Matt Greenberg and Lassina
Dembélé have described algorithms that work in different levels of
generality. In joint work with Cameron Franc, we propose a p-adic
approach to this problem, via understanding quotients of Bruhat-Tits
buildings.

In this talk we will give an introduction to this subject and explain

Iterated period integrals and multiple Hecke L-functions

Posted in
Speaker: 
Kentaro Ihara
Date: 
Thu, 2011-07-21 15:00 - 16:00
Location: 
MPIM Lecture Hall
Parent event: 
MPI-Oberseminar

I introduce the multiple Heche L-function associated to elliptic cuspforms and discuss the relations
among special values of the function. Around 2005, Y.I. Manin introduced a generalization of the
period integralof cusp forms by using iterated integral (as an analogy of the iterated integral
expression of the 'multiple zeta values') and studied variousproperties.

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