Weekly Calendar

September 10-14, 2001

Monday Tuesday Wednesday Thursday Friday

Seminars Announcements Conferences Calendar Archive

Items for inclusion in the Weekly Calendar should be submitted via e-mail to Hilda Britt. Deadline for inclusion in the Weekly Calendar is 5 p.m. Thursdays. Speakers are encouraged to provide abstracts.

Orange & Blue Bar

MONDAY, SEPTEMBER 10

  
RAP ``Etale cohomology",  159 Altgeld Hall,  10:00 a.m.
  
Mr. Josh Mullet
Presheaves and sheaves

  
Math 400 - Introduction to Graduate Mathematics,  245 Altgeld Hall,  4:00 p.m.
  
Professor John Sullivan
Geometric Knot Theory


TUESDAY, SEPTEMBER 11

  
Symplectic and Contact Geometry RAP,  143 Henry,  10:00 a.m.
  
Professor Eugene Lerman
Group actions on contact manifolds
  
Abstract: We discuss the basics of group actions on contact manifolds. We define contact manifolds, group actions, discuss the existence of moment maps, contact quotients, convexity results.

  
Max Newman Topology,  345 Altgeld,  11:00 a.m.
  
Mike Mandell (Univ. of Chicago)
Cochains and Homotopy Type

  
RAP ``Spaces of non-positive curvature'',  243 Altgeld Hall,  11:00 a.m.
  
Professor Ilya Kapovich
Mk-complexes, cont.
  
Abstract: We will describe so called Mk-complexes, which are metric spaces obtained by gluing polyhedral pieces of the model space Mk. We shall also explore when an Mk-complex has curvature bounded above by k.

  
Several Complex Variables Seminar,  243 Altgeld Hall,  12:00 p.m.
  
Professor Robert Kaufman
Function Algebras and Several Complex Variables, II

  
Probability and Statistics Seminar,  2 Illini Hall,  11:00 p.m.
  
Professor Michael R. Kosorok (University of Wisconsin-Madison)
Semiparametric Inference for Proportional Hazards Frailty Regression Models
  
Abstract: We consider inference for proportional hazards frailty regression models which are one parameter extensions of the Cox proportional hazards model for right-censored data. These frailty models can significantly improve on the prediction accuracy of the Cox model. We develop fully efficient estimation methods and establish consistency and asymptotic normality for all parameters including the baseline hazard. We also prove the validity of the bootstrap and demonstrate that Markov chain Monte Carlo can be used for inference when profiling over the baseline hazard. The moderate sample size properties of the proposed procedures are explored in a simulation study, and the technique is illustrated with an analysis of non-Hodgkin's lymphoma data.

  
Analytic and Elementary Number Theory,  243 Altgeld Hall,  1:00 p.m.
  
Professor Paul Bateman (UIUC)
Famous conjectures in number theory (historical survey)

  
Differential Geometry Seminar,  347 Altgeld Hall,  1:00 p.m.
  
Mr. Chris Willett
The topological structure of contact and symplectic quotients
  
Abstract: This is joint work with E. Lerman. We show that if a Lie group acts properly on a co-oriented contact manifold preserving the contact structure, then the contact quotient is topologically a stratified space; i.e, a neighborhood of a point is isomorphic to the product of a disk with a cone on a compact stratified space. It follows from this result that symplectic quotients for proper Hamiltonian group actions are topologically stratified in this sense, simplifying previous work of L. Bates, E. Lerman, and R. Sjamaar.

  
Logic Seminar,  241 Altgeld Hall,  1:00 p.m.
  
Professor Lou van den Dries
Hausdorff limits and Gromov-Hausdorff limits of definable spaces
  
Abstract: This concerns some improvements of results I talked about last semester. A better organization of the material makes previous exposure to it unnecessary.

  
Special Analysis Seminar,  447 Altgeld Hall,  1:00 p.m.
  
Professor Haskell Rosenthal (UT, Austin)
Characterizations of the projection lattice of a von-Neumann algebra

  
Geometric Potpourri Seminar,  243 Altgeld Hall,  2:00 p.m.
  
Professor Richard Bishop (UIUC Department of Mathematics)
Circular Billiard Tables, Caustics, and Conjugate Loci
  
Abstract: Billiard paths on a circular billiard table are essentially the same as geodesics in a double disk, so they can be studied from the viewpoint of Riemannian geometry. The major concepts that are explained in this context are conjugate points, the Morse index of the energy function on a path space, the enumeration of distinct geodesics joining two points, focal points of submanifolds, and the exponential map. The conjugate and focal loci are made from caustics of fields of light rays reflected by a circular arc, some of which were identified long ago by Huygens to include the cardioid and what was later (Proctor, 1879) called the nephroid. A unified approach based on Euclidean geometry is given for the calculation of the parametric equations of caustics of all orders, and consequently of conjugate loci. The interior geometry of the disk can be any constant-curvature metric.

  
Stochastic and Nonlinear Analysis,  347 Altgeld Hall,  2:00 p.m.
  
Frederi Viens (Purdue University)
Lower (and hopefully sharp upper) bounds on the almost sure Lyapunov exponent for a Stochastic PDE.
  
Abstract: It had been known for several years that the stochastic heat equation on Zd with small diffusion coefficient k and linear multiplicative potential [W\dot](s,x), where [W\dot](s,x) is space-time white-noise in [0,¥)×Zd, has an almost-sure exponential behavior in large time with a rate that is bounded above and below by quantities of the form K/log(1/k) with universal constants K. One of the main techniques used was the representation of the equation's solution via the stochastic Feynman-Kac formula. Using this formula, and a new percolation technique, Mike Cranston has allegedly proved that upper and lower bounds are equal, by identifying the exact value of K. In continuous space, R. Carmona and I proved that the same upper bound holds, leaving the issue of the lower bound open. However, in order to use the Feynman-Kac representation in Rd, and especially in the case d ³ 2, the potential W must be a bonafide function in space. In this talk we will show that there is no reason to believe that the upper bound is always sharp, by showing how to obtain a lower bound of the form kb/(b+1) in the case of a potential that is almost-surely a-Hölder-continuous in the space parameter for all a < b but not for a = b.

  
RAP on Geometric Representation Theory,  345 Altgeld Hall,  2:30 p.m.
  
Professor William Haboush
Chapter 2 of Chriss and Ginzburg
  
Abstract: We will discuss the Bialynicki-Birula decomposition and results on fixed point reduction. Time permitting we will begin to discuss Borel Moore homology.

  
Commutative Ring Theory Seminar,  243 Altgeld Hall,  3:00 p.m.
  
Per Jensen
"The Grassmannian".
http://www.math.uiuc.edu/ ssather/MATH/crt_fa01.html

  
Graph Theory and Combinatorics,  241 Altgeld Hall,  3:00 p.m.
  
Professor Nikolai Kuzjurin (Institute for System Programming Russian Academy of Sciences (Moscow))
On asymptotically good packings and coverings
  
Abstract: In 1985, V.Rödl proved the long-standing conjecture of Erdos and Hanani about the existence of asymptotically good packings and coverings of l-subsets of an n-element set by k-subsets. In this talk we will consider the problem of finding threshold functions k = k(n) for the existence of such packings and coverings. It appears that the thresholds for packings and coverings differ.

  
Study Seminar on Harmonic Analysis,  347 Altgeld Hall,  3:00 p.m.
  
Dr. Jorge Rivera-Noriega
Harmonic analysis in locally flat domains
  
Abstract: We are studying the paper of C. Kenig and T. Toro on harmonic analysis in localy flat domains

  
Decision Control Laboratory - Topics in Systems,  141 CSL,  3:30 p.m.
  
Kurt Plarre (Coordinated Science Laboratory, University of Illinois at Urbana-Champaign)
Graphical Models: Probabilistic Inference
  
Abstract: I will describe the Junction Tree Algorithm which is used to calculate probability distribution efficiently for Graphical Models. I will describe some applications.


WEDNESDAY, SEPTEMBER 12

  
RAP ``Etale cohomology",  159 Altgeld Hall,  10:00 a.m.
  
Professor Marco Schlichting
The category of sheaves

  
Decision, Control and Optimization Seminars,  B02 CSL,  3:00 p.m.
  
Dr. M. Vidyasagar (Tata Consultancy Services, Advanced Technology)
Learning with Dependent Inputs
abstractThe classical PAC learning formulation is based on the assumption that the inputs to the learning algorithm are statistically independent. This assumption effectively restricts PAC learning to just 'static' nonlinearities. In this talk, it is shown that whenever a simple inequality holds, any algorithm that learns with independent inputs will continue to learn with beta-mixing input sequences. In particular, for concept classes, distribution-free learning, fixed-distribution learning, and learning under a compact family of probability measures, are all preserved when the inputs are beta-mixing instead of being independent.

  
RAP - Conformal invariance, intersection exponents and critical percolation,  145 Altgeld Hall,  4:00 p.m.
Speaker and topic TBA

  
Information Protection Seminar,  114 CSRL,  4:30 p.m.
Nathan Whitehead
Towards a hyperelliptic curve chip
  
Abstract: Progress report on work done over Summer to implement hyperelliptic curve arithmetic on a chip.


THURSDAY, SEPTEMBER 13

  
Math - Physics (BCDE) Lunch Seminar,  6-110 Engineering Science Bldg,  12:05 p.m.
  
Professor Sheldon Katz (UIUC)
Geometry of Large N Dualities, II

  
Several Complex Variables Seminar,  243 Altgeld Hall,  12:00 p.m.
  
Bernhard Lamel (Doob Research Asst. Prof)
Mapping Problems in Several Complex Variables, II

  
Analytic and Elementary Number Theory,  243 Altgeld Hall,  1:00 p.m.
  
Professor Doug Bowman (UIUC)
Fun fractions
  
Abstract: I will discuss some elementary aspects of continued fractions, including certain parts of the theory neglected in usual treatments.

  
Group Theory,  347 Altgeld Hall,  1:00 p.m.
  
Professor Derek Robinson (UIUC)
Algorithms for Polycyclic-by-Finite Groups, II
  
Abstract: In this series of talks a survey of known algorithms for PF-groups will be given. Then new algorithms to test surjectivity of derivations will be presented, with application to the problem of deciding of two given subgroups of a PF-group permute.

  
RAP Seminar on Noncommutative Lp spaces,  345 Altgeld Hall,  1:00 p.m. (cont. at 3:00 p.m.)
  
Anthony Kye Yew (Grad Student, UIUC)
Introduction to noncommutative Lp spaces with trace, III
  
Abstract: Realization of noncommutative Lp-spaces as unbounded operators.
  
Pedro Pointevin (Grad Student, UIUC)
Introduction to noncommutative martingales
  
Abstract: Introduction to noncommutative conditional expectations and maringales

  
Algebraic Number Theory,  241 Altgeld Hall,  2:00 p.m.
  
Mr. You-Chiang Yi
Elliptic curves of small prime conductor
  
Abstract: We will discuss why there is only one isogeny class of elliptic curves of conductor 11. If time permits, we will talk about the case of conductor 19.

  
Analysis Seminar,  243 Altgeld Hall,  2:00 p.m.
  
Joseph Rosenblatt (Department Chair)
Forcing Divergence
  
Abstract: Given that the supremum of a sequence of positive functions is not integrable, one can construct conditional expectations operators and ergodic averages which make the sequence diverge almost everywhere.

  
Knot Theory RAP,  345 Altgeld Hall,  2:00 p.m.
  
Professor Brinkmann (J. L. Doob Research Assistant Professor)
Introduction to knot theory

  
Commutative Ring Theory Seminar,  243 Altgeld Hall,  3:00 p.m.
  
Per Jensen
"The Grassmannian" (cont.).
http://www.math.uiuc.edu/ ssather/MATH/crt_fa01.html

  
*** RESCHEDULED FOR OCTOBER 11 ***
Mathematics Colloquium,  245 Altgeld,  4:00 p.m.
  
Tomasz Luczak (Adam Mickiewicz University, Poznan, Poland and Emory University, Atlanta, Georgia)
Sum-Free Sets
  
Abstract: A subset of A of a semigroup is sum-free if it contains no solutions to the equation x+y = z. In the talk we present some open problems and recent results concerning the structure and the number of sum-free subsets of natural numbers and abelian groups
Refreshments at 3:15 pm in Room 321 Altgeld Hall


FRIDAY, SEPTEMBER 14

  
RAP ``Etale cohomology",  159 Altgeld Hall,  10:00 a.m.
  
Professor Marco Schlichting
The category of sheaves (cont.)

  
RAP - Conformal invariance, intersection exponents and critical percolation,  145 Altgeld Hall,  4:00 p.m.
Speaker and topic TBA

  
Model Theory Seminar,  141 Altgeld Hall,  4:00 p.m.
  
Mr. Thomas Rohwer
Module definable sets in a field of Laurent series
  
Abstract: Let k be a finite field of characteristic p, K = k((x)) the field of Laurent series over k, and R = K[F] the ring of twisted polynomials over K with respect to the commuting relation Fl = lp F for all l in K. K is a left R module using the natural action of K on K and letting F act as l® lp. Some results on the structure of solution sets of linear equations (and projections of these) in the module K will be presented.

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On 7 Sep 2001, 11:42.
Last modified September 12, 2001