Mathematics

Time quasi-periodic gravity water waves in finite depth

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.

Morse-Bott cohomology from homological perturbation

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.

Language edit distance, $(\min,+)$-matrix multiplication & beyond

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.

Billiards in quadrilaterals, Hurwitz spaces, and real multiplication of Hecke type

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.

Topological and combinatorial methods in Theoretical Distributed Computing

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.

Our Mathematical Universe

Max Tegmark
Professor, Massachusetts Institute of Technology
May 8, 2015
In this lecture, Tegmark surveys how humans have repeatedly underestimated not only the size of the cosmos, but also the power of the human mind to understand it using mathematical equations. He explores how mathematics in physics has allowed us to predict Neptune, radio waves, and the Higgs bosons. Tegmark also discusses how we should think of ourselves in a cosmic perspective.