COGSChicago Operator algebra and Group theory SeminarOrganized by Kate Juschenko and Emily Peters
Upcoming:Adam Marcus, Yale University "Controlling Eigenvalues (at least in theory) part 2" Thursday, November 21, 4pm. Abstract: In the late 80's and early 90's Bourgain and Tzafriri published a series of influential papers regarding the KadisonSinger problem. One result from that work in particular has been used effectively in a number of areas is what has come to be known as "Restricted Invertibility." I will show how the method of interlacing polynomials can be used to reprove this result with asymptotically sharp constants. Then I will discuss how those same proof techniques were extended in the proof of KadisonSinger. Past speakers:Collin Bleak, University of St Andrews. "De Bruijn Automorphisms of the Full Shift" Thursday, October 23, 2pm. Linguistics Department Seminar Room (2016 Sheridan Road). (joint seminar with Northwestern Algebra Seminar)
Abstract: We investigate a set of groups {SBC_n}. Each group SBC_n sits very naturally in the full group of automorphisms of {0,1, ... , n1}^Z, the full shift on n letters, and is somehow a very natural object. Still, the structure of each group SBC_n, at least initially, was quite a mystery.
Yash Lodha, Cornell. "A new solution to the von NeumannDay problem for finitely presented groups." 15 October 2014. Abstract: In this talk, I will describe a finitely presented subgroup of s group of piecewise projective homeomorphisms of the real line. This in particular provides a new example of a finitely presented group which is nonamenable and yet does not contain a nonabelian free subgroup. The example is moreover torsion free. A portion of this is joint work with Justin Moore. Higher finiteness properties will be discussed if time permits. Darren Creutz, Vanderbilt. "Operator Algebraic Superrigidity for Lattices and Commensurators." 3 December 2013. Robin TuckerDrob, Rutgers. "Shiftminimal groups, fixed price 1, and the unique trace property." 11 December 2013.
