In this talk I present some differential equation perturbed by the fast motion of a particle in a cylinder corresponding to the Z-periodic Lorentz gas, a model introduced by H.A Lorentz in 1905. I will discuss there are one of the natural ways to…

# Categoria evento: Dynamical Systems Seminar

## Around the Danzer Problem and the construction of dense forests – Faustin Adiceam (Université Paris-Est Créteil)

A 1965 problem due to Danzer asks whether there exists a set with finite density in Euclidean space (i.e. « not containing too many points ») intersecting any convex body of volume one. A suitable weakening of the volume constraint leads one to the…

## Open random dynamics and return time statistics – Jason Atnip (University of Queensland)

In this talk we discuss recent results concerning the return time statistics for deterministic and random dynamical systems. Taking a perturbative approach, we consider a decreasing sequence of holes in phase space which shrink to a point. For…

## Rigidity for time-changes of unipotent flows – Mauro Artigiani (Universidad del Rosario)

Parabolic flows form an intermediate category between elliptic and hyperbolic flows. They exhibit some characteristics associated with non-chaotic systems, and some associated with highly chaotic ones. A fundamental example is the horocycle flow on…

## Monodromy kernels for strata of abelian differentials – Riccardo Giannini (University of Glasgow)

In this talk, we are going to talk about the topology of the moduli space of translation surfaces. These are closed Riemann surfaces with a flat metric on the complement of some finite number of points, around which the metric is given by cyclically…

## Rational approximations to linear subspaces – Nicolas de Saxcé (CNRS, Université Paris-Nord 13)

Dirichlet’s theorem in Diophantine approximation implies that for any real x, there exists a rational p/q arbitrarily close to x such that |x-p/q|<1/q^2. In addition, the exponent 2 that appears in this inequality is optimal, as seen for example by…

## The Markoff spectrum on the Hecke group – Dong Han Kim (Dongguk University)

We consider the Markoff spectrum on the Hecke group. The Markoff spectrum on H4 is known as the Markoff spectrum of index 2 sublattices by Vulakh and the Markoff spectrum of 2-minimal forms or C-minimal forms by Schmidt, who characterized the…

## Continued fraction expansions of algebraic power series over a finite field – Yann Bugeaud (Université de Strasbourg)

Almost nothing is known on the continued fraction expansion of an algebraic real number of degree at least three. The situation is different over the field of power series Fp((x−1)), where p is a prime number. For instance, there are algebraic power…

## Irrational numbers and where to find them – Simon Kristensen (Aarhus University)

While all but countably many real numbers are irrational (and even transcendental), it is preciously difficult to decide whether this is the case for concrete real numbers, unless some special reason is apparent. For instance, we all know…

## Mixing of simple symmetric random walks on the circle – Klaudiusz Czudek (IST, Austria)

Fix an irrational number $\alpha$ and a smooth, positive, real function $p$ on the circle. A particle at a point $x$ in the circle jumps to $x+\alpha$ with probability $p(x)$ or to $x−\alpha$ with probability $1−p(x)$. In 1999 Sinai investigated…