September 8 |
Kristin Courtney, UVaThe full C*-algebra of the free group on two generatorsThis talk will center around the similarly titled paper by Man-Duen Choi (appearing in print in 1980). I will provide a brief description of the full group C*-algebra for a locally compact Hausdorff group as well as a useful characterization for the full group C*-algebra for the free group on two generators in terms of universal pairs of unitaries. We will see why this C*-algebra with abundant ideals is, in fact, a primitive C*-algebra with no nontrivial projections, which can also be faithfully represented as a *-subalgebra of a countable direct sum of finite-dimensional matrix algebras. |
September 15 |
No meeting |
September 22 |
Craig Kleski, Miami University (Ohio)Classifying C*-algebras generated by representations of nilpotent groupsGroup C*-algebras come in many flavors, with few general results known about their structure. In this talk, I explain how to classify C*-algebras generated by faithful irreducible representations of the unitriangular group UT(4,Z). In principle, this allows for an explicit decomposition of the C*-algebra as an inductive limit of tractable C*-algebras and thus reveals much information. I will review relevant parts of K-theory for C*-algebras and the Elliott program, and try to convince you why you should care about UT(4,Z). This is joint work with Caleb Eckhardt and Paul McKenney. |
September 29 |
Kristin Courtney, UVaThe full C*-algebra of the free group on two generatorsContinuation from September 8. |
October 6 |
Reading day (no meeting) |
October 13 |
Kevin Beanland, Washington and Lee UniversityClasses of operators determined by ordinal indicesWe will discuss some newly discovered closed two-sided operator ideals that are defined using ordinals. The classes of operators are defined using a generalization of Bourgain's tree index. The is joint work with Ryan Causey, Dan Freeman and Ben Wallis. |
October 20 |
Chris Ramsey, UVaC*-algebras isomorphic after tensoring with M_{n}In 1977 Joan Plastiras gave a striking example of two non *-isomorphic C*-algebras A and B such that M_{2}(A) and M_{2}(B) are isomorphic. But what happens when we amp up this question? If M_{n}(A) and M_{n}(B) are isomorphic for every n > 1 does this imply that A and B are isomorphic? The answer, care of a plucky Dane, is quite delightful and will lead us on a merry jaunt through some interesting theory. |
October 27 |
Ali Kavruk, Virginia Commonwealth UniversityRelative weak injectivity for C*-algebrasExtending C. Lance`s weak expectation property, E. Kirchberg introduced the notion of relative weak injectivity for arbitrary pairs of C*-algebras. In this presentation we focus on non-commutative versions of several order theoretic concepts such as tight Riesz interpolation and decomposition properties and Arveson-Riesz extension properties with their connection to relative weak injectivity. We exhibit several examples of these notions in the category of Kadison and Banach spaces, which in turn, yield characterizations for simplicial and Lindenstrauss spaces. We discuss several formulations of Connes` embedding problem via Arveson-Riesz extension properties. For general operator systems, by extending some of the result of E. Effros, we formulate function theoretic characterization of (c,max) nuclearity, which distinguishes the C*-systems among the others. Time permitting, we will discuss weak rigidity for operator systems, a joint work with C. Kleski. |
November 3 |
Isabelle Chalendar, Université Lyon IOn the compactness of truncated Toeplitz operatorsTruncated Toeplitz operators are the compressions of Toeplitz operators on model spaces. In a joint work with E. Fricain and D. Timotin, we investigate the property of compactness for these operators through natural embedding measures associated with these operators.Nate Brown (Penn State) will give the department colloquium on November 5. VOTCAM will be held at Washington & Lee University on November 7. |
November 10 |
No seminar |
November 17 |
Elias Katsoulis, East Carolina UniversityCrossed product constructions in operator algebra theory |
November 24 |
No seminar... last work hour before Thanksgiving break. |
December 1 |
No seminar. There will be an analysis lecture series by Stuart White (University of Glasgow) probably December 3-4. |