Oregon State University

Wed 28 Sep 2016, 3:00pm
Probability Seminar
ESB 2012

Some probability theory that arises from worrying about NavierStokes and other quasilinear equations

ESB 2012
Wed 28 Sep 2016, 3:00pm4:00pm
Abstract
The success of probability theory in the analysis of linear, or even certain semilinear, parabolic and elliptic pde’s is well documented. In spite of various attempts to find a stochastic foothold for the analysis of NavierStokes equations and related quasilinear equations, the problem remains a substantial challenge. That said, the quest can lead to new stochastic structures and problems that relate to modern probability in fundamental ways. In this talk I will try to indicate this with a few explicit examples largely stemming from the LejanSznitman multiplicative cascade/branching random walk framework for NavierStokes equations.
This talk is primarily based on recent joint work with Radu Dascaliuc, Nicholas Michalowski, and Enrique Thomann with partial support from the National Science Foundation.
hide

University of Illinois, Urbana–Champaign

Wed 28 Sep 2016, 3:15pm
Topology and related seminars
ESB 4133 (PIMS Lounge)

An equivariant motivic slice filtration

ESB 4133 (PIMS Lounge)
Wed 28 Sep 2016, 3:15pm4:15pm
Abstract
Mixing Voevodsky's filtration in motivic homotopy and Dugger's in C_2equivariant homotopy theory leads to an interesting filtration on the C_2equivariant motivic homotopy category. In this talk, I'll introduce these slice filtrations and talk about some joint work with P. A. Ostvaer, where we compute the resulting zero slice of the equivariant motivic sphere spectrum.
hide

UBC Math

Fri 30 Sep 2016, 3:00pm
Department Colloquium
ESB 2012

UBC Mathematics and PIMS Faculty Award Colloquium  On the local Langlands conjectures

ESB 2012
Fri 30 Sep 2016, 3:00pm4:00pm
Abstract
The Langlands program, initiated in the 1960s, is a set of conjectures predicting a unification of number theory and the representation theory of groups. More precisely, the Langlands correspondence provides a way to interpret results in number theory in terms of group theory, and vice versa.
In this talk we sketch a few aspects of the local Langlands correspondence using elementary examples. We then comment on some questions raised by the emerging "mod p" Langlands program.
hide

Department of Computer Science, UBC

Tue 4 Oct 2016, 12:30pm
Scientific Computation and Applied & Industrial Mathematics
ESB 4133 (PIMS Lounge)

Fast Iterative Solvers for CahnHilliard Problems

ESB 4133 (PIMS Lounge)
Tue 4 Oct 2016, 12:30pm1:30pm
Abstract
The CahnHilliard equation models the motion of interfaces between several phases. The underlying energy functional includes a potential for which different types were proposed in the literature. We consider smooth and nonsmooth potentials with a focus on the latter. In the nonsmooth case, we apply a function spacebased algorithm, which combines a MoreauYosida regularization technique with a semismooth Newton method. We apply classical finite element methods to discretize the problems in space. At the heart of our method lies the solution of large and sparse fully discrete systems of linear equations. Block preconditioners using effective Schur complement approximations are presented. For the smooth systems, we derive optimal preconditioners, which are proven to be robust with respect to crucial model parameters. Further, we prove that the use of the same preconditioners give poor approximations for the nonsmooth formulations. The preconditioners we present for the nonsmooth problems incorporate the regularization terms. Extensive numerical experiments show an outstanding behavior of our developed preconditioners. Our strategy applies to different CahnHilliard problems including phase separation and coarsening processes, image inpainting, and twophase flows.
hide

University of California at Irvine

Tue 4 Oct 2016, 3:30pm
Diff. Geom, Math. Phys., PDE Seminar
ESB 2012

On the first eigenvalue estimate for subLaplacian and Kohn Laplacian and Rigidity Theorems on pseudoHermitian CR manifolds

ESB 2012
Tue 4 Oct 2016, 3:30pm4:30pm
Abstract
In this talk, I will present a CRversion of LichnerowiczObata type theorem in a closed pseudoHermitian CR manifolds. It includes the lower bound estimates for the first positive eigenvalue for the both subLaplacian and Kohn Laplacian. I will also provide Obata type theorem associated to the subLaplacian and Kohn Laplacian on a closed pseudoHermitian manifold. As an application, we give some rigidity theorem when lower bound of eigenvalue is achieved. This is based on a joint work with X. Wang and a joint work with Duong N. Son and Wang. I will also talk about some ongoing work in this topic.
hide

UBC

Tue 4 Oct 2016, 4:00pm
Discrete Math Seminar
ESB 4127

Forbidden Berge hypergraphs

ESB 4127
Tue 4 Oct 2016, 4:00pm5:00pm
Abstract
hide
