# Events for 10/02/2019 from all calendars

## Student Working Seminar in Groups and Dynamics

Time: 1:00PM - 2:00PM

Location: BLOC 628

Speaker: James O'Quinn

Title: Topological full groups, amenability, and G-odometers

Abstract: Topological full groups were first introduced by Giordano,Putnam, and Skau as an invariant related to orbit equivalence for minimal cantor systems. However, more recent interest has been given to these groups because they provide examples of groups with interesting properties related to amenability. In this talk, I will give an overview of some of the basic concepts of topological dynamics, as well as introduce topological full group and the concept of amenability. The goal is to explicitly describe the structure of the topological full groups coming from G-odometers, following a paper of Cortez and Medynets."

## Number Theory Seminar

Time: 1:45PM - 2:45PM

Location: BLOC 220

Speaker: Qibin Shen, University of Rochester

Title: v-adic multiple zeta values over function fields

Abstract: In this talk we will discuss the zero distribution, $\mathbb{F}_q-$, and $\mathbb{F}_q(t)-$ linear relations of interpolated v-adic multiple zeta values over function fields. We will give some combinatorial universal families of algebraic relations hold for multiple zeta values, multiple zeta star values, truncated multiple zeta values, interpolated and motivic v-adic multiple zeta values. We will also introduce our conjecture for the dimension of the linear span of the v-adic multiple zeta values and some interesting behavior of these values.

## Noncommutative Geometry Seminar

Time: 2:00PM - 3:00PM

Location: BLOC 628

Speaker: Clément Dell'Aiera, University of Hawai'i

Title: Exhaustivity of representations at infinity of Roe algebras

Abstract: Exhaustive representations were introduced by Nistor and Prudhon, motivated by characterizations of Fredholm operators and spectral theory of N-body Hamiltonians. Coarse geometry deals with the geometry at infinity of metric spaces with bounded geometry via the Roe algebra. In particular, Spakula and Willlett show how to construct a family of representations of the Roe algebra which can be thought of "the representations at infinity". We will be studying when this family is exhaustive. This is joint work with Yu Qiao.

## Committee P&T Meeting

Time: 4:00PM - 5:00PM

Location: BLOC 220

Speaker: Committee P&T Meeting, Texas A&M University

Time: 4:00PM - 5:00PM

Location: BLOC 628

Speaker: Jun Sur Richard Park

Title: Hierarchical multiscale finite element method for multi-continuum media

Abstract: Computing the effective coefficients of the homogenized equations can be expensive because one needs to solve local cell problems for a large number of macroscopic points. We develop a hierarchical approach for solving cell problems at a dense network of macro-scopic points with an essentially optimal computation cost. The method employs the fact that neighboring representative volume elements (RVEs) share similar features; and effective properties of the neighboring RVEs are close to each other. The hierarchical approach reduces computation cost by using different levels of resolution for cell problems at different macroscopic points. We prove rigorously that this hierarchical method achieves the same level of accuracy as that of the full solve where cell problems at every macroscopic point are solved using the FE spaces with the highest level of resolution, but at the essentially optimal computation cost. We present some numerical results that computes effective permeabilities of a two scale multi-continuum system via the numerical solutions of the cell problems. We prove the homogenization convergence for our multiscale multi-continuum system.

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