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WEEKLY CALENDAR |
| Monday 21 |
2:10-3 pm, room 1320. Special Talk. Paul Baum, Penn State University.
What is K-theory and what is it good for?
4:10-5:30 pm, room 1432. Subfactor Seminar. Jesse Peterson, UC Berkeley. Group cocycles and the ring of affiliated operators. I will present some results (joint work with Andreas Thom) on cocycles from a group into its left regular representation and also into the ring of affiliated operators of the group von Neumann algebra. Specifically I will be interested in when a group $\Gamma$ has positive first $\ell^2$-Betti number. I will include a strong generalization of a result of L\"{u}ck and Gaboriau which states that if $\Lambda$ is a finitely generated normal subgroup of a group $\Gamma$ with $0 < \beta_1^{(2)}(\Gamma) < \infty$ then either $|\Lambda| < \infty$ or $[\Gamma : \Lambda] < \infty$. I will also include applications about the structure of $C_r^*(\Gamma)$ and as time permits. |
| Tuesday 22 |
4:10-5 pm, room 1431. Special Talk. Paul Baum, Penn State University. K-theory and K-homology.
4:10-5:30 pm, room 1432. Universal Algebra and Logic Seminar. Carmela Sica, University of Salerno. Centralizers in locally finite groups. Let G be a locally finite group admitting an automorphism f of finite order such that the centralizer C_G(f) satisfies certain finiteness conditions. What impact does this have on the structure of the group G? Starting from some nown results, it will be shown that if G is locally finite and admits a four-group of automorphisms without non-trivial fixed points, then the derived subgroup G' is a product of normal nilpotent subgroups. This is joint work with Pavel Shumyatsky. |
| Wednesday 23 | 2:10-3 pm, room 1320. Special Talk. Paul Baum, Penn State University. The universal example for proper actions. |
| Thursday 24 |
1:10-2 pm, room 1214. Special Talk. Paul Baum, Penn State University. K-theory for group C*-algebras.
4:10-5 pm, room 5211. Colloquium. Anna Gilbert, University of Michigan. (Fast) algorithms for compressed sensing. "Compressed sensing" captures a new paradigm which connects sparse representations, high-dimensional geometry, probability, and algorithms. It suggests a new paradigm in information acquisition and processing of compressible signals. These signals can be approximated using an amount of information much smaller than the nominal dimension of the signal. Traditional approaches acquire the entire signal and process it to extract the information. The new approach acquires a small number of nonadaptive linear measurements of the signal and uses sophisticated algorithms to determine its information content. Emerging technologies can compute these general linear measurements of a signal at unit cost per measurement. I will discuss the connections to randomized algorithms and signal processing. In particular, I will focus on extremely fast algorithms and measurement designs for compressed sensing, including some prototype hardware designs. Tea at 3:30 pm in SC 1425. |
| Friday 25 | 3:10 pm, room 1310. Graph Theory and Combinatorics Seminar. Anthony Hilton, Reading University. Degree bounded factorizations of bipartite multigraphs and of pseudographs. Abstract is available at http://www.math.vanderbilt.edu/~calendar/factorizations_abstract.pdf |