Regularity of weakly stable codimension 1 CMC varifolds

Neshan Wickramasekera
University of Cambridge; Member, School of Mathematics
January 15, 2019
The lecture will discuss recent joint work with C. Bellettini and O. Chodosh. The work taken together establishes sharp regularity conclusions, compactness and curvature estimates for any family of codimension 1 integral $n$-varifolds satisfying: (i) locally uniform mass and $L^{p}$ mean curvature bounds for some $p > n;$ (ii) two structural conditions and (iii) two variational hypotheses on the orientable regular parts, namely, stationarity and (weak) stability with respect to the area functional for volume preserving deformations (supported on the regular parts).

Distribution of the integral points on quadrics

Naser Talebi Zadeh Sardari
University of Wisconsin Madison
January 9, 2019
Motivated by questions in computer science, we consider the problem of approximating local points (real or p-adic points) on the unit sphere S^d optimally by the projection of the integral points lying on R*S^d, where R^2 is an integer. We present our numerical results which show the diophantine exponent of local point on the sphere is inside the interval [1, 2-2/d]. By using the Kloosterman's circle method, we show that the diophantine exponent is less than 2-2/d for every d>3.

Barcodes and $C^0$ symplectic topology

Sobhan Seyfaddini
ENS Paris
December 17, 2018
Hamiltonian homeomorphisms are those homeomorphisms of a symplectic manifold which can be written as uniform limits of Hamiltonian diffeomorphisms. One difficulty in studying Hamiltonian homeomorphisms (particularly in dimensions greater than two) has been that we possess fewer tools for studying them. For example, (filtered) Floer homology, which has been a very effective tool for studying Hamiltonian diffeomorphisms, is not well-defined for homeomorphisms.