Seminar Calendar
for events the day of Thursday, April 21, 2011.

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Thursday, April 21, 2011

Number Theory Seminar
1:00 pm   in 241 Altgeld Hall,  Thursday, April 21, 2011
 Del Edit Copy
Submitted by pppollac.
 Maria Sabitova (CUNY Math)Twisted root numbers of elliptic curves over local fields with residual characteristic 3Abstract: Root numbers are signs in functional equations for L-functions. In this talk I will discuss local twisted root numbers attached to elliptic curves, i.e., signs in functional equations for L-functions attached to an elliptic curve over a local field twisted by a Galois representation. In the computation of local root numbers attached to elliptic curves the most difficult case is when elliptic curves have wild ramification, i.e., when the residual characteristic p of the base field is 2 or 3. The purpose of this talk is to report on results in the case when p=3.

Group Theory Seminar
1:00 pm   in Altgeld Hall 347,  Thursday, April 21, 2011
 Del Edit Copy
Submitted by kapovich.
 Desmond Cummins (UIUC Math)A geometric introduction to S-machinesAbstract: The S-machine is a model of computation that was first introduced by Mark Sapir. Although an S-machine can be formally defined as a rewriting system consisting of a finite set of rules that act on the set of words is some finite alphabet, a more natural definition can be given in which the S-machine is defined to be a certain type of finitely presented HNN extension of a free group. Using this defintion, computations of the S-machine can be interpreted as VanKampen diagrams over the corresponding finite group presentation. In this talk I will formally define S-machines as finite group presentations and then prove some basic structural results about the VanKampen diagrams that correspond to computations of S-machines.

Analysis Seminar
2:00 pm   in 243 Altgeld Hall,  Thursday, April 21, 2011
 Del Edit Copy
Submitted by aimo.
 Pekka Salmi (University of Waterloo)Idempotent states on locally compact quantum groupsAbstract: An idempotent state on a locally compact group is just a probability measure that is an idempotent with respect to the convolution. The Kawada-Ito theorem characterizes such idempotent states as the normalised Haar measures of compact subgroups. On the dual side, idempotent states on group C*-algebras are characteristic functions of open subgroups. In this talk we consider idempotent states on co-amenable locally compact quantum groups and discuss the connections between idempotent states, quantum subgroups and invariant C*-subalgebras. This is joint work with Adam Skalski.