2008-09 Abstracts

September 9 Louis Rowen (Bar Ilan University)   
Supertropical algebra
   Recent recent in "tropical geometry" has focused on the max-plus algebra, a semiring whose structure unfortunately is rather limited. Recently Z. Izhakian introduced a newer algebraic structure (which we call a supertropical algebra) containing the max-plus algebra, whose algebraic theory is much richer and enables us to prove analogs of many of the classical theorems from commutative algebra in this setting.


September 11 Sasha Kleshchev (University of Oregon/UVa)   
Recent developments in representation theory of symmetric groups
  We will review some recent developments in representation theory of symmetric groups. We will start with the (relatively) new approach by Okounkov and Vershik in characteristic 0, and explain its counterpart in characteristic p, which leads to deep connections with Kac-Moody algebras, crystal graphs, canonical bases, and ideas of categorification.
October 2 Rafael Benguria (P. Universidad Catolica de Chile)   
The zeroes of the Fourier transform of the characteristic function of a domain and their relation with the eigenvalues of the Laplacian
  Consider the Fourier transform of the characteristic function of a bounded, smooth domain in the Euclidean space in n dimensions. I will present some recent results concerning the relation between the closest zero of this function and both Dirichlet and Neumann Eigenvalues of the Laplacian on that domain. I will motivate the results with simple examples. I will also discuss some open problems in this area. This is joint work with M. Levitin (Cardiff) and Leonid Parnovski (University College, London).
October 9 Ruth Williams (UCSD)   
Stochastic networks with resource sharing
  Stochastic networks are used as models for complex systems involving dynamic interactions subject to uncertainty. Application domains include manufacturing, the service industry, telecommunications, and computer systems. Networks arising in modern applications are often highly complex and heterogeneous, with network features that transcend those of conventional queueing models. The control and analysis of such networks present challenging mathematical problems. In this talk, a concrete application will be used to illustrate a general approach to the study of stochastic networks using more tractable approximate models. Specifically, we consider a data network model that represents the randomly varying number of flows present in a network where bandwidth is shared fairly amongst elastic documents. This model, introduced by Massoulie and Roberts, can be viewed as a stochastic network with simultaneous resource possession. Elegant fluid and diffusion approximations will be used to study the performance of this model. The talk will conclude with a summary of the current status and description of open problems associated with the further development of approximate models for general stochastic networks. This talk is based in part on joint work with W. N. Kang, F. P. Kelly, and N. H. Lee.

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