Nebraska-Iowa Iowa-Nebraska Functional Analysis Seminar 

General Format

This is a one-day mathematics conference held once or twice a year, usually in April in Omaha, Nebraska and in October in Des Moines, Iowa. The format consists of four hour-long talks, with a one-and-a-half or two hour lunch. between the 2nd and 3rd talk. The first talk typically starts at 11:00 am and the last talk finishes about 5:00 pm.

In Des Moines, we usually meet at The University of Iowa John and Mary Pappajohn Education Center, located at 1200 Grand Ave., Des Moines, IA 50309. Here is a map. (For many years, we met on the campus of Drake University, and we are grateful for their support.) 

In Omaha, we usually meet on the campus of Creighton University.

The conference first met in March of 1994; the April 2014 meeting represented the twentieth year and the twenty-seventh meeting. (There have not been two meetings every year.) 

It is jointly organized by the Mathematics Departments of Creighton University, Iowa State University, The University of Iowa, and The University of Nebraska-Lincoln. Faculty and students from a number of other nearby universities also attend. All are welcome. There is no registration fee. If you have any questions, please contact one of the organizers. 


Randall Crist of Creighton 

Raul Curto of Iowa 

Yiu T Poon of Iowa State 

Allan Donsig of Nebraska-Lincoln 

Next Meeting: October 8, 2022 in Des Moines

When the meeting is scheduled and as speakers scheduled, the names, titles, and abstracts will be posted here.

Eric Weber (of Iowa State University) 

Title: Vector-valued de Branges-Rovnyak spaces

Abstract:  Model spaces are the subspaces of the Hardy space that are invariant under the back- ward shift and provide a replacement for the spectral theorem for the backward shift. General- izations of these subspaces are known as de Branges-Rovnyak spaces. De Branges introduced a vector valued version of these spaces via a generalization of the Herglotz representation for inner functions. I’ll discuss the construction as well as some of the scalar theory that passes to the vector case, and some of the scalar theory that doesn’t. These spaces arise in the construction of Fourier series expansions for fractal measures in dimensions 2 and above, and the fractal measures play a central role in the description of which parts of the scalar theory extends to the vector theory. This is joint work with John Herr and Palle Jorgensen.

Baruch Solel, (of the Technion, Haifa) 

Title: Function Theory and W-Categories

Abstract: Free nc function theory is an extension of the theory of holomorphic functions of several complex variables to the theory of functions on matrix tuples Z = (Z-1,··· ,Z_d) where Z_i is an n by n complex matrix and n is allowed to vary. 

An nc function is a function defined on such tuples Z and takes values in nNMn(C) which is graded and respects direct sums and similarity (equivalently, respects intertwiners).

The classical correspondence between positive kernels and Hilbert spaces of functions has been recently extended by Ball, Marx and Vinnikov to nc completely positive kernels and Hilbert spaces of nc functions.

In a previous, unpulished work, we have developed a similar theory for matricial functions where C is replaced by a von Neumann algebra M, nNMn(C) is replaced by a suitable disjoint union of correspondences over M and the “index set” N is replaced by the set of representations of M.

In this talk I will discuss a work in progress where we extend these results further to study functions (and kernels) that are invariant under certain actions of W-categories.

This is a joint work with Paul Muhly.

Paul Herstedt, (of Grinnell College) 

Title: TBA 

Ionut Chifan, (of the University of Iowa) 

Title: Wreath-like product groups and their applications to the study of von Neumann algebras 

Abstract: We will present several applications of wreath-like product groups to the structural theory of II_1 factors with property (T). Using quotienting techniques from geometric group theory, including Dehn filling, we will introduce a new class of wreath-like product groups which have peripheral structure. Exploiting this concept in combination with a new von Neumann algebraic reconstruction method we will show there exist uncountably many property (T) groups G which are completely recognizable from their von Neumann algebras, $L(G)$; in particular, they satisfy Connes Rigidity Conjecture. In addition, we will show that many of these groups are reconstructible from their reduced $C^*$ -algebras, $C^*_r (G)$ as well. 

In a different direction, making use of the wreath-like product groups, we will prove that every separable tracial von Neumann algebra embeds into a $II_1$ factor with property (T) which can be taken to have trivial outer automorphism and fundamental groups.  

This is based on a joint work with Adrian Ioana, Denis Osin and Bin Sun and a recent joint work with Daniel Drimbe and Adrian Ioana.

Speakers and Titles from Previous Meetings 

Gary Weiss (of University of Cinncinnati) Madras, India) 

Title: The commutator structure of operator ideals and unitarily invariant trace extensions beyond the trace class 

Michael Lamourexu (of University of Calgary) 

Title: Ideals in Continuous Crossed products 

Paul Muhly (of University of Iowa) 

Title: On the Morita equivalence of C*-correspondences 

Roger Smith (of Texas A&M University) 

Title: Cohomology of von Neumann algebras with Cartan subalgebras 

October 11, 1997

May Nilsen (of the University of Nebraska-Lincoln) 

Title: Hopf C*-algebras 

Randall Crist (of Creighton University) 

Title: Derivations on TAF Algebras 

Nik Weaver (of Washington University in St. Louis) 

Title: Metrics from the Point of View of Functional Analysis) 

Radu Gologan (of the University of Iowa and the Institute of Mathematics of Romanian Academy of Sciences) 

Title: Pointwise Ergodic Theorems 

April 26, 1997

Teresa Bermudez (of the University of Iowa and University de Laguana, Spain) 

Title: Some Results in Local Spectral Theory 

Dale Buske (of Iowa State University and St. Cloud State University) 

Title: Hilbert Modules over a class of Semicrossed Products 

Bryan Cain (of Iowa State University) 

Title: Operator Equations, Inertia, and Stability 

Eui-Chai Jeong (of the University of Iowa) 

Title: Decomposition of the Cuntz Algebra Representation