MenuEvents for 10/20/2017 from all calendars
Roman Kogan, dissertation defense
Time: 10:00AM - 12:00PM
Location: Blocker 506A
Speaker: Roman Kogan
Postdoc Lunch Time Talks
Time: 12:00PM - 12:20PM
Location: BLOC 220
Speaker: Benben Liao, Texas A&M University
Description: Title: Group actions and non-commutative ergodic Theorems
Abstract: Starting from the work of Birkhoff, ergodic theory is one of the central themes in dynamical system. In this talk, we give a review of generalizations of ergodic Theorems with group actions and non-commutative measure spaces (von Neumann algebras), and show an ergodic theorem for groups with polynomial growth acting on von Neumann algebras. This is based on joint work with G. Hong and S. Wang.
Postdoc Lunch Time Talks
Time: 12:35PM - 12:55PM
Location: BLOC 220
Speaker: Rob Rahm, Texas A&M University
Description: Title: A Dyadic Version of The Hilbert Transform and Other Operators.
Abstract: Consider the Hilbert transform (convolution with 1/x). For which measures is this operator bounded on L^2(\mu) and what is its norm in terms of "geometric" properties of the measure? We use a dyadic approximation to this (and other) operators to prove the desired estimates.
Postdoc Lunch Time Talks
Time: 12:55PM - 1:15PM
Location: BLOC 220
Speaker: Emanuele Ventura, Texas A&M University
Description: Title: Waring and tensor ranks
Abstract: The problem of expressing a homogeneous polynomial as a sum of powers of linear forms is very classical and
goes back to the work of Sylvester, Hilbert, Scorza and many others. The rank of a homogeneous polynomial is
the smallest number of linear forms such that the polynomial admits such a representation. The tensor rank
is the analogous notion for tensors. In this talk, we will introduce these notions
through examples and describe directions of current research.
Mathematical Physics and Harmonic Analysis Seminar
Time: 1:50PM - 2:50PM
Location: BLOC 628
Speaker: Wen Feng, University of Kansas
Title: Stability of Vortex solitons for n-dimensional focusing NLS
URL: Event link
Algebra and Combinatorics Seminar
Time: 3:00PM - 3:50PM
Location: BLOC 117
Speaker: Benjamin Schröter, TU-Berlin
Title: Multi-splits in hypersimplicies and split matroids
Abstract: Multi-splits are a class of coarsest regular subdivisions of convex polytopes. In this talk I will present a characterization of all multi-splits of two types of polytopes, namely products of simplices and hypersimplices. It turns out that the multi-splits of these polytopes are in correspondence with one another and matroid theory is the key in their analysis, as all cells in a multi-split of a hypersimplex are matroid polytopes. Conversely, the simplest case of multi-splits of hypersimplices give rise to a new class of matroids, which we call split matroids. The structural properties of split matroids can be exploited to obtain new results in tropical geometry.
Geometry Seminar
Time: 4:00PM - 5:00PM
Location: BLOC 628
Speaker: Michael Di Pasquale, Oklahoma State University
Title: Homological Obstructions to Freeness of Multi-arrangements
Abstract:
If the module of vector fields tangent to a multi-arrangement is free over the underlying polynomial ring, we say that the multi-arrangement is free. It is of particular interest in the theory of hyperplane arrangements to investigate the relation of freeness to the combinatorics of the intersection lattice - the holy grail here is Terao's conjecture that freeness of arrangements is detectable from the intersection lattice. It is known that corresponding statements for multi-arrangements fail.
Given a multi-arrangement, we present a co-chain complex derived from work of Brandt and Terao on k-formality whose exactness encodes freeness of the multi-arrangement. The cohomology groups of this co-chain complex thus present obstructions to freeness of multi-arrangements. Using this criterion we give an example showing that the property of being totally non-free is not detectable from the intersection lattice. This builds on previous work with Francisco, Schweig, Mermin, and Wakefield.
