Lyapunov exponents for small random perturbations of predominantly hyperbolic two dimensional volume-preserving diffeomorphisms, including the Standard Map

Alex Blumenthal
University of Maryland
November 19, 2018
An outstanding problem in smooth ergodic theory is the estimation from below of Lyapunov exponents for maps which exhibit hyperbolicity on a large but non- invariant subset of phase space. It is notoriously difficult to show that Lypaunov exponents actually reflect the predominant hyperbolicity in the system, due to cancellations caused by the“switching” of stable and unstable directions in those parts of phase space where hyperbolicity is violated.

Translators for Mean Curvature Flow

David Hoffman
Stanford University
November 13, 2018
A translator for mean curvature flow is a hypersurface $M$ with the property that translation is a mean curvature flow. That is, if the translation is
$t\rightarrow M+t\vec{v}$, then the normal component of the velocity vector $\vec{v}$ is equal to the mean curvature $\vec{ H}$. I will discuss recent joint work with Tom Ilmanen, Francisco Martin and Brian White, specifically our classification of the the complete translators in $R^3$ that are graphical, and the construction of new families of complete translators that are not graphical.

Morse-Theoretic Aspects of the Willmore Energy

Alexis Michelat
ETH Zurich
November 13, 2018
We will present the project of using the Willmore elastic energy as a quasi-Morse function to explore
the topology of immersions of the 2-sphere into Euclidean spaces and explain how this relates to the
classical theory of complete minimal surfaces with finite total curvature.

This is partially a joint work in collaboration with Tristan Rivière.

Invertible objects in stable homotopy theory

Irina Bobkova
Member; School of Mathematics
November 12, 2018
Computation of the stable homotopy groups of spheres is a long-standing open problem in algebraic topology. I will describe how chromatic homotopy theory uses localization of categories, analogous to localization for rings and modules, to split this problem into easier pieces, called chromatic levels. Each chromatic level can be understood using the theory of deformations of formal group laws. I will talk about recent results, and work in progress, at the second chromatic level.

Distinguishing fillings via dynamics of Fukaya categories

Yusuf Baris Kartal
Massachusetts Institute of Technology
November 12, 2018
Given a Weinstein domain $M$ and a compactly supported, exact symplectomorphism $\phi$, one can construct the open symplectic mapping torus $T_\phi$. Its contact boundary is independent of $\phi$ and thus $T_\phi$ gives a Weinstein filling of $T_0\times M$, where $T_0$ is the punctured 2-torus. In this talk, we will outline a method to distinguish $T_\phi$ from $T_0\times M$ using dynamics and deformation theory of their wrapped Fukaya categories.