# 2017 - 2018

# Calendrier / Calendar

# MONTRÉAL

**Date Heure/Time**: Le vendredi 24 novembre 2017 - 15:30

**Lieu/Venue**: Université McGill, Leacock Building, salle LEA 232

**Conférencier/Speaker**: David R. Bellhouse, Western University, London, Ontario

**Titre/Title**: 150 years (and more) of data analysis in Canada

**Resume/Abstract**:

As Canada celebrates its 150th anniversary, it may be good to reflect on the past and future of data analysis and statistics in this country. In this talk, I will review the Victorian Statistics Movement and its effect in Canada, data analysis by a Montréal physician in the 1850s, a controversy over data analysis in the 1850s and 60s centred in Montréal, John A. MacDonald’s use of statistics, the Canadian insurance industry and the use of statistics, the beginning of mathematical statistics in Canada, the Fisherian revolution, the influence of Fisher, Neyman and Pearson, the computer revolution, and the emergence of data science.

**Date Heure/Time**: Le vendredi 24 novembre 2017 - 16:00

**Lieu/Venue**: CRM, Université de Montréal, Pavillon André-Aisenstadt, salle 6254

**Conférencier/Speaker**: Stanislav Smirnov, , University of Geneva and Skolkovo Institute of Science and Technology

**Titre/Title**: Complex analysis and 2D statistical physics

**Resume/Abstract**:

Over the last decades, there was much progress in understanding 2D lattice models of critical phenomena. It started with several theories, developed by physicists. Most notably, Conformal Field Theory led to spectacular predictions for 2D lattice models: e.g., critical percolation cluster a.s. has Hausdorff dimension $91/48$, while the number of self-avoiding length $N$ walks on the hexagonal lattice grows like $(\sqrt{2+\sqrt{2}})^N N^{11/32}$. While the algebraic framework of CFT is rather solid, rigorous arguments relating it to lattice models were lacking. More recently, mathematical approaches were developed, allowing not only for rigorous proofs of many such results, but also for new physical intuition. We will discuss some of the applications of complex analysis to the study of 2D lattice models.

**Date Heure/Time**: Le vendredi 17 novembre 2017 - 16:00

**Lieu/Venue**: UQAM, Pavillon Président-Kennedy, 201, ave du Président-Kennedy, salle PK-5115

**Conférencier/Speaker**: Jun-Cheng Wei, UBC

**Titre/Title**: Recent progress on De Giorgi Conjecture

**Resume/Abstract**:

Classifying solutions to nonlinear partial differential equations are fundamental research in PDEs. In this talk, I will report recent progress made in classifying some elementary PDEs, starting with the De Giorgi Conjecture (1978). I will discuss the classification of global minimizers and finite Morse index solutions, relation with minimal surfaces and Toda integrable systems, as well as recent exciting developments in fractional De Giorgi Conjecture.

**Date Heure/Time**: Le vendredi 27 octobre 2017 - 16:00

**Lieu/Venue**: UdeM, Pavillon André-Aisenstadt, salle 6254

**Conférencier/Speaker**: Justin Solomon, MIT

**Titre/Title**: Beneath the Surface: Geometry Processing at the Intrinsic/Extrinsic Interface

**Resume/Abstract**:

Algorithms for analyzing 3D surfaces find application in diverse fields from computer animation to medical imaging, manufacturing, and robotics. Reflecting a bias dating back to the early development of differential geometry, a disproportionate fraction of these algorithms focuses on discovering intrinsic shape properties, or those measurable along a surface without considering the surrounding space. This talk will summarize techniques to overcome this bias by developing a geometry processing pipeline that treats intrinsic and extrinsic geometry democratically. We describe theoretically-justified, stable algorithms that can characterize extrinsic shape from surface representations. In particular, we will show two strategies for computational extrinsic geometry. In our first approach, we will show how the discrete Laplace-Beltrami operator of a triangulated surface accompanied with the same operator for its offset determines the surface embedding up to rigid motion. In the second, we will treat a surface as the boundary of a volume rather than as a thin shell, using the Steklov (Dirichlet-to-Neumann) eigenproblem as the basis for developing volumetric spectral shape analysis algorithms without discretizing the interior.

**Date Heure/Time**: Le vendredi 13 octobre 2017 - 16:00

**Lieu/Venue**: UdeM, Pavillon André-Aisenstadt, salle 6254

**Conférencier/Speaker**: Avi Soffer, Rutgers University

**Titre/Title**: Supercritical Wave Equations

**Resume/Abstract**:

I will review the problem of Global existence for dispersive equations, in particular, supercritical equations. These equations who play a fundamental role in science, have been , and remain a major challenge in the field of Partial Differential Equations. They come in various forms, derived from Geometry, General Relativity, Fluid Dynamics, Field Theory. I present a new approach to classify the asymptotic behavior of wave equations, supercritical and others, and construct global solutions with large initial data. I will then describe current extensions to Nonlinear Schroedinger Equations.

**Date Heure/Time**: Le vendredi 29 septembre 2017 - 16:00

**Lieu/Venue**: UdeM, Pavillon André-Aisenstadt, salle 1140

**Conférencier/Speaker**: John H. Conway, Princeton University

**Titre/Title**: The first field

**Resume/Abstract**:

The “first field” is obtained by making the entries in its addition and multiplication tables be the smallest possibilities. It is really an interesting field that contains the integers, but with new addition and multiplication tables. For example, 2 x 2 = 3, 5 x 7 = 13, ... It extends to the infinite ordinals and the first infinite ordinal is the cube root of 2!

**Date Heure/Time**: Le vendredi 15 septembre 2017 - 16:00

**Lieu/Venue**: UQAM, Pavillon Président-Kennedy, 201, ave du Président-Kennedy, salle PK-5115

**Conférencier/Speaker**: Siyuan Lu, Rutgers University, Lauréat 2017 du Prix Carl Herz / 2017 Carl Herz Prize Winner

**Titre/Title**: Isometric embedding and quasi-local type inequality

**Resume/Abstract**:

In this talk, we will first review the classic Weyl's embedding problem and its application in quasi-local mass. We will then discuss some recent progress on Weyl's embedding problem in general Riemannian manifold. Assuming isometric embedding into Schwarzschild manifold, we will further establish a quasi-local type inequality. This talk is based on works joint with Pengfei Guan and Pengzi Miao.