
Date Time 
Location  Speaker 
Title – click for abstract 

09/01 4:00pm 
BLOC 220 
Gilles Pisier TAMU 
Completely Sidon sets in discrete groups


09/08 4:00pm 
BLOC 220 
Gilles Pisier TAMU 
Completely Sidon sets in C*algebras


09/22 4:00pm 
BLOC 220 
Amudhan KrishnaswamyUsha TAMU 
Nilpotent elements of operator ideals are single commutators
Pearcy and Topping asked in '71 if every compact operator can be written as a single additive commutator [B,C]=BCCB of compact operators. While the general problem is still open, we show that every nilpotent operator in an operator ideal is a single commutator of operators from some power of the operator ideal; where the exponent depends on the degree of nilpotency. This is joint work with Ken Dykema. 

09/29 4:00pm 
BLOC 220 
Scott LaLonde University of Texas at Tyler 
Fell bundles: Unifying C*algebras associated to groupoids
Fell bundles provide one with an abstract notion of groupoid actions on C*algebras. As a result, they provide a unifying framework in which to study many of the C*algebras that are often associated to groupoids, including the groupoid C*algebra, groupoid crossed products, and twisted versions of both constructions. We will discuss some recent work on Fell bundles, including a powerful stabilization result of Ionescu, Kumjian, Sims, and Williams that relates an arbitrary Fell bundle to a canonical groupoid crossed product. We focus on some consequences of this theorem in the context of nuclearity and exactness for Fell bundle C*algebras, as well as some connections to exact groupoids and groupoid extensions.


10/13 4:00pm 
BLOC 220 
Mehrdad Kalantar University of Houston 
Superrigidity relative to subgroups
We present several ergodic theoretical and operator algebraic superrigidity results for discrete groups relative to their subgroups. These results are obtained by analyzing the restriction of boundary actions to subgroups. This is joint work with Yair Hartman. 

10/27 4:00pm 
BLOC 220 
Michael Brannan TAMU 
Amenable quantum groups are not always unitarizable
A wellknown theorem of Day and Dixmier from around 1950 states that if G is an amenable locally compact group, then any uniformly bounded representation of G on a Hilbert space is similar to a unitary representation. In short, amenable groups are ``unitarizable''. In this talk, I will focus on the question of whether a version of the DayDixmier unitarizability theorem holds in the more general framework of locally compact quantum groups. It turns out that the answer to this question is no: In joint work with SangGyun Youn (Seoul National University), we show that many amenable quantum groups (including all DrinfeldJimboWoronowicz qdeformations of classical compact groups) admit nonunitarizable uniformly bounded representations. 

11/04 09:00am 
U. Houston 
Brazos Analysis Seminar 
Brazos Analysis Seminar
https://sites.google.com/site/brazosanalysisseminar/ 

11/05 09:00am 
U. Houston 
Brazos Analysis Seminar 
Brazos Analysis Seminar
https://sites.google.com/site/brazosanalysisseminar/ 

11/10 4:00pm 
BLOC 220 
Florin Boca University of Illinois at UrbanaChampaign 
Farey statistics and the distribution of eigenvalues in large sieve matrices
Some parts of the fine distribution of Farey fractions (a.k.a. roots of unity) is captured
by their spacing statistics (consecutive gaps and correlations). A large sieve matrix is a N x N matrix
A*A, where A is a Vandermonde type matrix defined by roots of unity of order at most Q. The classical
large sieve inequality provides an upper bound estimate for the largest eigenvalue of A*A. This talk
will discuss some connections between these topics. We will focus on the behavior of these matrices
when N ~ cQ^2, with Q > infty and c>0 constant, establishing asymptotic formulas for their moments
and proving the existence of a limiting distribution for their eigenvalues as a function of c. This
is joint work with Maksym Radziwill.


11/17 4:00pm 
BLOC 220 
Anna Skripka University of New Mexico 
Schur multipliers in perturbation theory.
Schur multipliers and their generalizations have been actively studied
for over a century. Classical linear Schur multipliers act on matrices
as entrywise multiplications; multilinear Schur multipliers act by
some intricate products. After recalling finite dimensional Schur
multipliers, we will concentrate on their generalizations to
multilinear transformations arising in infinite dimensional
perturbation theory and consider an application to approximation of
operator functions. In particular, we will discuss sharp conditions
for Schatten class membership of remainders of approximations [1]. The
affirmative case relies on the approach to Schur multipliers without
separation of variables emerging from [3] and addressed in the
nonselfadjoint case in [2].
[1] "Multilinear Schur multipliers and applications to operator Taylor
remainders", with D. Potapov, F. Sukochev, and A. Tomskova, Adv.
Math., 320 (2017), 10631098.
[2] "Estimates and trace formulas for unitary and resolvent comparable
perturbations", Adv. Math., 311 (2017), 481509.
[3] "Spectral shift function of higher order", with D. Potapov and F.
Sukochev, Invent. Math., 193 (2013), no. 3, 501538. 

12/01 4:00pm 
BLOC 220 
Li Gao University of Illinois at UrbanaChampaign 
TBA
TBA 