AMSI/AustMS AGR National Seminar: The C*-algebras of right-angled Artin-Tits monoids

7 July, 3.00pm AEDT

Speaker's Name:

Professor Søren Eilers

Speaker's Institution:

The University of Copenhagen

Title of Seminar:

AMSI/AustMS AGR National Seminar: The C*-algebras of right-angled Artin-Tits monoids

Host Institution:

University of Wollongong

Time and Date:

Monday 7 July, 3.00pm AEST

Seminar Abstract:

The right-angled Artin groups and semigroups are defined from undirected graphs by associating a generator to each vertex, and imposing commutativity on a pair of generators exactly when they are connected by an edge. In a completely similar vein, one can study operators on Hilbert spaces which are required to commute according to data arising from the graph. Recent insight has clarified the sense in which this latter definition is founded on the former for semigroups.

Employing classification theory for non-simple C*-algebras, we have obtained a complete description of these right-angled Artin semigroup C*-algebras by their K-theory, which reflects the geometry of the graph through the Euler characteristic. Among many other things, this leads to surprisingly strong results on the stability of such operators, showing that if a familiy of operators satisfy the relevant relations up to a small error, then they can be perturbed a bit to obtain an exact match.

This is joint work with Xin Li and Efren Ruiz.

Speaker Bio:

Professor Søren Eilers received his PhD from the University of Copenhagen in 1995. He was appointed immediately to an assistant professorship at Copenhagen, and was promoted to full Professor in 2008. He has held numerous visiting positions at international institutions like the Fields Institute in Toronto, the Mittag-Leffler institute in Stockholm, and MSRI at Berkeley, and was the president of the Danish Mathematical Society from 2006 to 2008.

Søren’s research interests lie primarily in the areas of symbolic dynamics and of operator algebras. He has contributed to the study of invariants for symbolic-dynamical systems, to the theory of stability of relations for C*-algebras, and to C*-algebraic representation theory for various sorts of dynamical systems. In recent years, Søren has instigated a program of classification of non-simple C*-algebras by K-theoretic invariants. This program has taken great strides forward and is now a major international research focus which continues to grow apace.

Seminar Convenor:

This email address is being protected from spambots. You need JavaScript enabled to view it.

AGR IT support:

This email address is being protected from spambots. You need JavaScript enabled to view it.