## Ramanujan complexes and golden gates in PU(3).

In their seminal works from the 80's, Lubotzky, Phillips and Sarnak proved the following two results:

Shai Evra

Member, School of Mathematics

January 9, 2019

In their seminal works from the 80's, Lubotzky, Phillips and Sarnak proved the following two results:

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.

Massimiliano Berti

International School for Advanced Studies

November 8, 2017

We prove the existence and the linear stability of Cantor families of small amplitude time quasi-periodic standing water waves solutions, namely periodic and even in the space variable $x$, of a bi-dimensional ocean with finite depth under the action of pure gravity. Such a result holds for all the values of the depth parameter in a set of asymptotically full measure. This is a small divisor problem.

Eshan Chattopadhyay

Member, School of Mathematics

November 7, 2017

We present an explicit pseudorandom generator with seed length $\tilde{O}((\log n)^{w+1})$ for read-once, oblivious, width $w$ branching programs that can read their input bits in any order. This improves upon the work of Impaggliazzo, Meka and Zuckerman where they required seed length $n^{1/2+o(1)}$.

Zhengyi Zhou

University of California, Berkeley

November 6, 2017

Abstract: In this talk, I will give a new construction of the Morse-Bott cochain complex, where the underlying vector space is generated by the cohomology of the critical manifolds. This new construction has two nice features: (1) It requires the minimum amount of transversality. (2) The choices made in the construction do not depend on the moduli spaces. I will explain its relation to three other constructions in literature, namely Austin-Braam's push-pull construction, Fukaya's push-pull construction and the cascades construction.

Barna Saha

University of Massachusetts, Amherst

November 6, 2017

The language edit distance is a significant generalization of two basic problems in computer science: parsing and string edit distance computation. Given any context free grammar, it computes the minimum number of insertions, deletions and substitutions required to convert a given input string into a valid member of the language. In 1972, Aho and Peterson gave a dynamic programming algorithm that solves this problem in time cubic in the string length. Despite its vast number of applications, in forty years there has been no improvement over this running time.

Sanjeev Arora and Richard Zemel

October 27, 2017

François Lalonde

University of Montreal

March 24, 2017

Alexander Wright

Stanford University; Member, School of Mathematics

November 30, 2015

After a brief introduction to the dynamics of the $\mathrm{GL}(2,\mathbb R)$ action on the Hodge bundle (the space of translations surfaces), we will give a construction of six new orbit closures and explain why they are interesting. Joint work with Alex Eskin, Curtis McMullen, and Ronen Mukamel.

Dmitry Feichtner-Kozlov

Institute for Algebra, Geometry, Topology, and their Applications, University of Bremen

November 7, 2015

In the first half of the talk I will give a very compressed introduction into parts of Theoretical Distributed Computing from the point of view of mathematician. I will describe how to construct simplicial models whose combinatorics contains important information about computability and complexity of standard distributed tasks. In the second part, I will outline our recent progress on estimating the complexity of the so-called Weak Symmetry Breaking task, where we are able to derive some quite surprising results.