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Abstracts for Seminar on Algebra, Geometry and Physics

Alternatively have a look at the program.

Arithmetic as algebraic geometry

Posted in
Speaker: 
A. Smirnov
Date: 
Tue, 2012-02-07 14:00 - 15:00
Location: 
MPIM Lecture Hall

The talk will contain a short introduction to the F_1-program
and to the theory of generalized rings and schemes of N. Durov.
It is planned to represent certain unexpected features of the new
algebra and geometry and some recent results.


 

Quasi-smooth derived schemes and perfect obstruction theories

Posted in
Speaker: 
Timo Schuerg
Affiliation: 
Mainz/MPI
Date: 
Tue, 2012-02-21 14:00 - 15:00
Location: 
MPIM Lecture Hall

A very nice feature of quasi-smooth derived schemes (in the sense of Toen-Vezzosi and Lurie) is that they induce a  1-perfect obstruction theory on the underlying scheme. This gives rise to a virtual fundamental class on the underlying scheme. I will discuss in detail how this obstruction theory is induced. This requires reviewing some facts about the Postnikov decomposition and the cotangent complex of simplicial algebras.



The Atiyah Conjecture and submultiplicativity

Posted in
Speaker: 
Igor Mineyev
Affiliation: 
U. of Illinois at Urbana-Champaign/MPI
Date: 
Tue, 2012-02-28 14:00 - 15:00
Location: 
MPIM Lecture Hall

The Strengthened Hanna Neumann Conjecture (SHNC), a question about free
groups and graphs, can be stated in analytic terms using l^2 Betti
numbers. This gives a generalization of the statement of SHNC from graphs
to comlexes: submultiplicativity. This also relates SHNC to the integral
Atiyah Conjecture (AC), a question about the Murray-von Neumann dimension
of kernels of certain operators. AC is the analytic, and more general,
version of the Kaplansky's Zero-Divisors Conjecture. We will discuss the

Moduli space of curves and Infinite Dimensional Grassmannian

Posted in
Speaker: 
Jia-Ming (Frank) Liou
Date: 
Tue, 2012-02-28 15:00 - 16:00
Location: 
MPIM Lecture Hall

This project was motivated by string theory. We study the relation between
the topology of moduli space of curves and that of the Sato-Grassmannian
via the Krichever map. The Krichever map was discovered for solving certain
integrable systems, KdV, K.P.; Segal and Wilson showed that the Krichever
map is an embedding from the moduli space of curves with some geometric
data into the Sato-Grassmannian. We expressed image of the induced map of
the Krichever map in terms of lambda-classes and psi-classes and related

Blueprints - towards absolute arithmetics

Posted in
Speaker: 
Oliver Lorscheid
Affiliation: 
Wuppertal
Date: 
Tue, 2012-03-13 14:00 - 15:00
Location: 
MPIM Lecture Hall

The definition of a blueprint was initially motivated by Jacques Tits' idea of descending Chevalley
groups to F1: there was a need to go beyond Deitmar's F1-geometry attached to monoids by
including a relation on the formal sums in the elements of a monoid. Meanwhile it became clear that blueprints not only yield a satisfactory answer to Tits' problem, with applications to (idempotent
and tropical) semirings, but provide the natural background tounderstand certain aspects

Conjugacy in Braid Groups and related Problems + Applications in non-commutative cryptography

Posted in
Speaker: 
Arkadius Kalka
Affiliation: 
Bar Ilan/MPI
Date: 
Tue, 2012-03-20 14:00 - 15:00

We consider the conjugacy problem and its friends (simultaneous and subgroup conjugacy, double coset
problem etc.) in braid and Garside groups. We show how these problems naturally emerge in non-commutative public key cryptography and how they are related. At the end we consider left self-distributive (LD)
systems and my new idea of non-associative cryptography and apply there P. Dehornoy's shifted
conjugacy (and its generalizations).

 

On Quantizations of Hitchin and Beauville-Mukai integrable systems

Posted in
Speaker: 
Vladimir Roubtsov
Affiliation: 
Univ. d'Angers/MPI
Date: 
Tue, 2012-03-27 14:00 - 15:00
Location: 
MPIM Lecture Hall

Milnor Descent for Cohesive DG Categories

Posted in
Speaker: 
Oren Ben-Bassat
Affiliation: 
University of Haifa
Date: 
Tue, 2012-04-03 14:00 - 15:00
Location: 
MPIM Lecture Hall

For any curved differential graded algebra A, Block introduced a dg category
called P_A. When A is the Dolbeaut algebra of a compact complex manifold,
Block proved that the homotopy category of P_A is the bounded derived category
of coherent sheaves on the manifold.  His first paper can be found at
http://arxiv.org/abs/math/0509284

Because P_A is defined without the use of sheaves, its definition is motivated by
non-commutative geometry. After providing some historical context and defining the main

Error-correcting codes, Kolmogorov complexity, and thermodynamics

Posted in
Speaker: 
Yuri Manin
Date: 
Tue, 2012-04-10 14:00 - 15:00
Location: 
MPIM Lecture Hall

The set of all error--correcting block codes over a fixed alphabet  with $q$ letters 
determines a recursively enumerable set of  rational points in the unit square with
coordinates $(R,\delta )$:= {\it  (relative transmission rate, relative minimal distance).}
Limit points of this set form a closed subset, defined by $R\le \alpha_q(\delta )$, where
$\alpha_q(\delta )$ is a continuous decreasing function called {\it asymptotic bound.}
Its existence was proved by Yu.M. in 1981, but no approaches to the computation of

Elliptic hypergeometric integrals, superconformal indices, and anomalies

Posted in
Speaker: 
V.P. Spiridonov
Affiliation: 
BLTP, Dubna/MPI
Date: 
Tue, 2012-04-24 14:00 - 15:00
Location: 
MPIM Lecture Hall

Elliptic hypergeometric integrals (introduced by the  speaker in 2000) represent the
top known level of special functions  of hypergeometric type. They appear to describe
superconformal   indices of four-dimensional supersymmetric gauge field theories.
 Superconformal indices of theories related by the Seiberg  duality coincide as a
consequence of nontrivial identities  for corresponding integrals. In the talk we show
that 't Hooft  anomaly matching conditions for dual theories are related to

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