Nov
21
Di
Emanuele Delucchi, (Université de Fribourg): Not really linear algebra
Nov 21 @ 11:00 – 12:00

Matroids over hyperfields, introduced by Baker and Bowler in 2016, offer a new unifying vision encompassing matroids, vector spaces, and related ideas in tropical geometry. The key tool are hyperfields, i.e., algebraic structures akin to fields — but with multivalued addition.

In this talk I will define matroids over hyperfields, present some examples (especially as related to tropical geometry and oriented matroids) and I will discuss some of the first results in this very young subject (which can be understood as looking for a “linear algebra” over hyperfields). The exposition will not presuppose any special previous knowledge.

Nov
23
Do
Matthew Schrecker (Oxford): “Global entropy solutions for compressible, isentropic Euler equations with geometric effects”
Nov 23 @ 15:15 – 16:45

Abstract: I will discuss the application of the method of compensated compactness to the compressible, isentropic Euler equations under certain geometric assumptions, e.g. the case of fluid flow in a nozzle of varying cross-sectional area or the assumption of planar symmetry under special relativity. Under these assumptions, the equations reduce to the classical (or relativistic) one-dimensional isentropic Euler equations with additional geometric source terms. In this talk, I will explain how the classical strategy of DiPerna, Chen et. al. can be adapted to handle these more complicated systems and will highlight some of the difficulties involved in extending the techniques to the relativistic setting.

Nov
24
Fr
Klaus Kroy, (Universität Leipzig): to be announced
Nov 24 @ 11:00 – 12:30

Vortrag in der Reihe: Arbeitsgemeinschaft ANGEWANDTE ANALYSIS

Nov
28
Di
Paul Breiding, (MPI MIS, Leipzig): Random Spectrahedra
Nov 28 @ 10:00 – 11:00
Kristin Shaw, (MPI MIS, Leipzig): Designs as tropical varieties
Nov 28 @ 11:00 – 12:00

A T-design is a collection of subsets of a set X of size k, called “blocks”, such that every subset of X of size T is contained in lambda blocks. Examples of designs are magic and latin squares, Hadamard matrices, Steiner systems, finite projective planes, to name just a few.

From a T-design I will show how to construct a T-dimensional tropical variety of degree lambda. Then using this construction, I will interpret some operations on designs through an algebro-geometric lens. This work is very much in progress and comments/suggestions are welcome.

Nov
29
Mi
Workshop: Berlin-Leipzig workshop in analysis and stochastics (day 1)
Nov 29 @ 13:30 – 18:00

More information you can find on the conference homepage:

https://www.mis.mpg.de/calendar/conferences/2017/Berlin-LE-WS/index.html

Felix-Klein Colloquium: Günter M. Ziegler (Berlin)
Nov 29 @ 16:30 – 17:30

Semi-algebraic sets of integer points.

We look at sets of integer points in the plane,
and discuss possible definitions of when such a set
is “complicated” — this might be the case if it
is not the set of integer solutions
to some system of polynomial equations and inequalities.
Let’s together work out lots of examples,
and on the way let’s try to develop criteria
and proof techniques …

The examples that motivated our study come
from polytope theory: Many question of the type
“What is the possible pairs of
(number of vertices, number of edges)
for 5-dimensional polytopes?”
have been asked, many of them with simple and complete
answers, but in other cases the answer looks complicated.
Our main result says: In some cases it IS complicated!
(Joint work with Hannah Sjöberg.)

Nov
30
Do
Workshop: Berlin-Leipzig workshop in analysis and stochastics (day 2)
Nov 30 @ 09:00 – 18:00

More information you can find on the conference homepage:

https://www.mis.mpg.de/calendar/conferences/2017/Berlin-LE-WS/index.html

Marius Yamakou, (MPI MIS, Leipzig): to be announced
Nov 30 @ 15:00 – 16:30
Sauli Lindberg (Madrid): TBA
Nov 30 @ 15:15 – 16:45
Letzte Änderung: 15. Mai 2013