Events for 09/09/2015 from all calendars

Number Theory Seminar

Time: 1:45PM - 2:45PM

Location: BLOC 220

Speaker: Tamas Erdelyi, Texas A&M University

Title: Flatness and ultraflatness of the derivative sequence of unimodular polynomials

Abstract: A polynomial is called unimodular if each of its coefficients is a complex number of modulus one. We examine how far the derivative sequence of unimodular polynomials is from being ultraflat in Kahane's sense. The talk is a survey of a few recent results in this direction.

Noncommutative Geometry Seminar

Time: 2:00PM - 3:00PM

Location: BLOC 628

Speaker: Branimir Ćaćić, Texas A&M University

Title: Good quotients of noncommutative Riemannian manifolds

Abstract: If the quotient of a compact Hausdorff space by a suitable group action is again a compact Hausdorff space, then the C*-algebra of the quotient is simply the fixed point subalgebra of the C*-algebra of the original space. If the quotient of a compact oriented Riemannian manifold by a suitable Lie group action is again a compact oriented Riemannian manifold, what happens at the level of spectral triples? In this talk, I will discuss an unbounded KK-theoretic construction of a good quotient for the spectral triple corresponding to a generalised Dirac operator equivariant under a free, orientation-preserving, and isometric smooth action of a compact connected Lie group. As time permits, I will then discuss applications to explicit unbounded KK-theoretic factorisations of noncommutative principal bundles arising via Rieffel's strict deformation quantisation. This is joint work with Bram Mesland.

Numerical Analysis Seminar

Time: 3:00PM - 4:00PM

Location: BLOC 628

Speaker: Pascal Azerad, Institut de Modélisation Mathématique de Montpellier

Title: Discretization of a conservation law with fractional anti-diffusion for dune morphodynamics

Abstract: We investigate finite differences discretizations of a nonlinear nonlocal equation recently introduced by A. C. Fowler to study the morphodynamics of river dunes. Due to the fractional anti-diffusive term, numerical stability must depend on the frequency range of the perturbation. We give sufficient stability criteria of fractional CFL type and show evidence of numerical convergence.

Student/Postdoc Working Geometry Seminar

Time: 3:00PM - 4:00PM

Location: Bloc 624

Speaker: JM Landsberg, TAMU

Title: The geometry of border rank algorithms for matrix multiplication

Abstract: I will describe surprisingly beautiful geometry associated to matrix multiplication algorithms that were discovered by numerical methods and computer searches.

Groups and Dynamics Seminar

Time: 3:00PM - 4:00PM

Location: BLOC 220

Speaker: Volodymyr Nekrashevych, Texas A&M University

Title: On full groups of etale groupoids

Abstract: Topological full groups of etale groupoids are natural generalizations of topological full groups of homeomorphisms (as defined by Giordano, Putnam, and Skau). H. Matui showed for some special classes of groupoids that the derived subgroup of the topological full group is simple and finitely generated. We introduce a special subgroup A(G) of the full group [[G]] of an etale groupoid G, and show that for all minimal groupoids the group A(G) is simple and is contained in every non-trivial normal subgroup of the full group. We also show that if G is expansive (e.g., the groupoid of an expansive action of a finitely generated group) then A(G) is finitely generated. For the groupoids studied by H. Matui the group A(G) coincides with the dervied subgroup of the full group.

AMUSE

Time: 6:00PM - 7:00PM

Location: BLOC 113

Speaker: Hetal Assar and Mukund Srinivas, Mu Sigma

Title: Moving from Big Data to Big Decisions