UIUC Mathematics Weekly Calendar

Weekly Calendar

February 26 - March 2, 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, FEBRUARY 26

341 Altgeld Hall, 2:00 p.m.: ANALYSIS SEMINAR; Professor W. B. Johnson,; NonLINEAR quotients and NONlinear quotients

245 Altgeld Hall, 4:00 p.m.: MATH 400 - INTRODUCTION TO GRADUATE MATHEMATICS; Professor Paul Schupp, Department of Mathematics, UIUC; Combinatorial and Geometric Group Theory - The Intersection of Group Theory, Geometry/Topology and Computability/Complexity

TUESDAY, FEBRUARY 27

345 Altgeld Hall, 11:00 a.m.: MAX NEWMAN TOPOLOGY; Manos Lydakis; title to be announced

243 Altgeld Hall, 12:00 p.m.: SEVERAL COMPLEX VARIABLES SEMINAR; Professor Alex Isaev, Canberra and UIUC; Actions of the Unitary Group on Complex Manifolds

241 Altgeld Hall, 1:00 p.m.: ANALYTIC NUMBER THEORY; Professor Vishwa Dumir, Panjab University, Chandigarh; Values of Non-homogeneous Indefinite Quadratic Forms: Part I

243 Altgeld Hall, 1:00 p.m.: LOGIC SEMINAR; Professor Mikhail Gavrilovitch; Exponentiation in Algebraically Closed Fields; Abstract: I will try to describe the recent works of Boris Zilber on complex numbers with exponentiation. We will discuss the model theoretic properties of this and other related structures, and how they are related to the Schanuel conjecture, tori intersection conjecture by Zilber, and a conjecture on solvability of systems of polynomial exponential equations.

345 Altgeld Hall, 2:00 p.m.: SPACES OF NON-POSITIVE CURVATURE RAP; Brad Edge, Department of Mathematics, UIUC; Basics of CAT(k) geometry

241 Altgeld Hall, 2:00 p.m.: STOCHASTIC AND NONLINEAR ANALYSIS; Peter Sternberg, Department of Mathematics, Indiana University, Bloomington; A Second Variation Argument for the Non-existence of Permanent Currents; Abstract: I will survey results over recent years on the existence of permanent currents within the context of the Ginzburg-Landau theory of superconductivity. Permanent currents are currents that circulate through a superconducting sample, sometimes for years, with only negligible resistance. Existence theories to date have relied on an assumption of either non-trivial topology or geometry of the sample. I will then present a new result on the non-existence of these currents in convex samples, obtained jointly with Shuichi Jimbo. The technique involves an analysis of the second variation of the energy. Before discussing elements of the proof, I will also survey related second variation non-existence arguments in the calculus of variations.

159 Altgeld Hall, 3:00 p.m.: COMMUTATIVE RING THEORY RAP; Professor Sean Sather-Wagstaff, Department of Mathematics, UIUC; Primes Associated to Graded Modules, after E. West

241 Altgeld Hall, 3:00 p.m.: GEOMETRIC POTPOURRI SEMINAR; Professor Peter Loeb, Department of Mathematics, UIUC; The geometry of the Morse Covering Theorem; Abstract:The Morse Covering Theorem, generalizing the theorem of Besicovitch from geometric measure theory, is one of the most powerful tools available for analysis on finite dimensional normed vector spaces and related manifolds. We briefly discuss some applications, and then give the geometric proof of a new öpen" version of the theorem.

345 Altgeld Hall, 3:00 p.m.: GRAPH THEORY AND COMBINATORICS; Professor Dimitry Fon-Der-Flaass; Embedding arbitrary graphs into strongly regular and distance regular graphs; Abstract: We show that every simple graph with n vertices is an induced subgraph of some strongly regular graph with fewer than 4n² vertices. Up to a constant factor, this coincides with the existing lower bound. We also show that every simple graph with n vertices is an induced subgraph of some distance regular graph of diameter 3 with fewer than 8n³ vertices.

141 CSRL, 3:30 p.m.

TOPIC IN SYSTEMS SEMINAR

Liang-Liang Xie, Coordinated Science Laboratory, UIUC

System Identification - An Introduction with a Recent Theoretical Result

Abstract: The speaker spent one year learning and working with Prof. Lennart Ljung and his group in Link–ping University, Sweden. They are one of the best in System Identification from both theory and application point of view. In this talk, the speaker tries to describe a picture of what he thinks of this area based on what he learnt and did during that year. Following are to be addressed:

1. System Identification is an art and practice of modeling the input-output data.

2. Some important issues to be considered in application.

3. What are the main problems to be considered in theory?

4. Some main theoretical results.

5. A recent theoretical progress.

Some technical details on 5: It has been well known for many years that the frequency function estimation error is inversely proportional to the signal-to-noise ratio at the frequency in question. Unfortunately this statement is only asymptotically correct as the model order goes to infinity. Some recent simulations show how misleading such approximation could be in the case of low order models. We will present a new expression on the frequency function estimation error, which holds exactly for any model order (unfortunately for a restricted class of models). The technical tricks are some orthonormal basis constructed based on the poles of the input-output dynamics.

WEDNESDAY, FEBRUARY 28

B02 CSRL, 3:00 p.m.: DECISION, CONTROL AND OPTIMIZATION SEMINAR; Dr. Mustafa Khammash, Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa; On Dynamics and Feedback Control in Biological Systems

114 CSRL, 4:30 p.m.: INFORMATION PROTECTION SEMINAR; H. Domazet, UIUC; An introduction to hyperelliptic curves

THURSDAY, MARCH 1

241 Altgeld Hall, 1:00 p.m.: ANALYTIC NUMBER THEORY; Professor Vishwa Dumir, Panjab University, Chandigarh; Values of Non-homogeneous Indefinite Quadratic Forms, part II

347 Altgeld Hall, 1:00 p.m.: GROUP THEORY SEMINAR; Ms. Donghi Lee; Premitivity preserving endomorphisms of free groups, continued; Abstract:We will continue to prove that every primitivity preserving endomorphism of a free group of a finite rank n „ 3 is an automorphism.

345 Altgeld Hall, 1:00 p.m.: NONSTANDARD ANALYSIS; Professor Yevgeniy Gordon; Kachurovskii's proof of ergodic theorem based on nonstandard analysis; Abstract: We continue to discuss the Thesis of Kachurovskii, where a new proof of ergodic theorem based on Rokhlin - Halmos Lemma and nonstandard analysis was introduced.

243 Altgeld Hall, 2:00 p.m.: ALGEBRAIC NUMBER THEORY; Professor Marcin Mazur, Department of Mathematics, UIUC; Introduction to abelian varieties, III

347 Altgeld Hall, 2:00 p.m.: ANALYSIS SEMINAR; See listing on Monday at 2:00 p.m.

145 Altgeld Hall, 3:00 p.m.: COLORING THEORY RESEARCH GROUP; Discussion of open problems

243 Altgeld Hall, 3:00 p.m.: COMMUTATIVE RING THEORY RAP; Andrew Richardson; The Frobenius Map, continued

347 Altgeld Hall, 3:00 p.m.: GALOIS MODULES; Professor Marcin Mazur, Department of Mathematics, UIUC; Application of trees and Euler systems to the lifted root number conjecture, continued

245 Altgeld Hall, 4:00 p.m.: MATHEMATICS COLLOQUIUM; Professor John H. Coates, FRS, Department of Pure Mathematics and Mathematical Statistics, University of Cambridge; Iwasawa theory of elliptic curves; Abstract: The first part of my lecture will discuss recent joint work with Schneider and Sujatha establishing the structure theory of finitely generated torsion modules over the Iwasawa algebra of a pro-p p-adic Lie group G. The second part will go on to describe what are perhaps the most interesting arithmetic examples of such modules which occur in nature, when we take the dual of the Selmer group of an elliptic curve without complex multiplication over the field generated by all its p-power division points. In this case, G is an open subgroup of GL₂(Z_p) by a celebrated theorem of Serre. We shall illustrate the theory by taking the prime p = 5 and the three primeval elliptic curves of conductor 11.; Refreshments at 3:15 pm in Room 321 Altgeld Hall

FRIDAY, MARCH 2

243 Altgeld Hall, 4:00 p.m.: MODEL THEORY SEMINAR; Mr. Matthias Aschenbrenner; Expansions of algebraically closed fields in o-minimal structures; Abstract:We continue to study the paper of Peterzil and Starchenko with the same title.