Weekly Calendar

April 16-20, 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, APRIL 16

245 Altgeld Hall, 4:00 p.m.
MATH 400 - INTRODUCTION TO GRADUATE MATHEMATICS
Professor Richard Sowers, Department of Mathematics, UIUC
Probability: From Analysis to Applications

TUESDAY, APRIL 17

345 Altgeld Hall, 11:00 a.m.
MAX NEWMAN TOPOLOGY
Laura Anderson, Texas A&M
Matroid Bundles

2 Illini Hall, 11:00 a.m.
PROBABILITY AND STATISTICS SEMINAR
No meeting this week

243 Altgeld Hall, 12:00 p.m.
SEVERAL COMPLEX VARIABLES SEMINAR
No meeting this week

241 Altgeld Hall, 1:00 p.m.
ANALYTIC NUMBER THEORY
Ae Ja Yee
Formulas of Ramanujan for the Coefficients of Certain Quotients of Eisenstein series

243 Altgeld Hall, 1:00 p.m.
LOGIC SEMINAR
Professor Lou ven den Dries, Department of Mathematics, UIUC
Gromov-Hausdorff limits of o-minimal spaces

243 Altgeld Hall, 2:00 p.m.
NONSTANDARD ANALYSIS
Professor Yevgeniy Gordon, Visitor, Nizhnii Novgorod State University
Kachurivskii's proof of ergodic theorem based on nonstandard analysis
Abstract: We continue to discuss the Thesis of Kachurivskii, where a new proof of ergodic theorem based on Rokhlin-Halmos Lemma and nonstandard analysis was introduced.

345 Altgeld Hall, 2:00 p.m.
SPACES OF NON-POSITIVE CURVATURE RAP
Professor Peter Brinkman, Department of Mathematics, UIUC
The Cartan-Hadamard Theorem, continued
Abstract: I will present the Cartan-Hadamard Theorem for complete connected metric spaces. This theorem strongly resembles the Cartan-Hadamard Theorem of Riemannian geometry because it uses local curvature conditions to draw powerful conclusions about the global geometry and topology of a space.

241 Altgeld Hall, 2:00 p.m.
STOCHASTIC AND NONLINEAR ANALYSIS
Dr. Sarah Patch, General Electric Medical Research
John's Ultrahyperbolic Equation and 3D CT @ GE
Abstract: Clinical computerized tomography data estimates line integrals of the patient's density; in '38 John showed that line integrals of well-behaved functions satisfy the ultrahyperbolic equations:
( \frac2hi  xj - \frac2hj  xi ) u(x; h) = 0        for i,j = 1,2,3
We will check that clinical CT systems measure boundary value data for John's equation(s) on a characteristic surface. We will quickly review the characteristic BV problem for the standard wave equation and then pull the same tricks in the Fourier domain to solve the above equation, providing unmeasured CT data which can be more easily reconstructed than the measured data lying on the characteristic surface. Preliminary numerical results will be presented.

159 Altgeld Hall, 3:00 p.m.
COMMUTATIVE RING THEORY RAP
Per Jensen
Projective Schemes

241 Altgeld Hall, 3:00 p.m.
GEOMETRIC POTPOURRI SEMINAR
Professor Margaret Symington, visiting UIUC from Georgia Institute of Technology
2-D pictures of 4-D manifolds - monodromy, affine structures and polygons
Abstract: I will describe some work in progress on classifying symplectic 4-manifolds with some additional structure (singular Lagrangian fibrations). This has led to a question about integral vectors in the plane arising from polygons that characterize the aforementioned manifolds. I will describe how to "read" the symplectic 4-manifold from data in the plane, how modifications of a polygon affect the 4-manifold, and translate a question about the 4-manifolds into a question about polygons. Input from the audience will be much appreciated.

345 Altgeld Hall, 3:00 p.m.
GRAPH THEORY AND COMBINATORICS
Professor Douglas West, Department of Mathematics, UIUC
On the Erdos-Simonovits-Sos Conjecture about the anti-Ramsey number of a cycle
Abstract: The anti-Ramsey number f(n,H) of a graph H is the maximum number of colors in an edge-coloring of Kn such that no copy of H has distinct colors on its edges. Let fk(n) denote the anti-Ramsey number of the cycle Ck. Erdos, Simonovits, and Sós provided a construction for each k that they conjectured to be optimal within an additive constant as n grows. Alon proved the conjecture for k £ 4 and proved a general upper bound about twice the conjectured value. We prove the conjecture for k £ 6 and improve the general upper bound by almost a factor of 2. (Joint work with Tao Jiang).

WEDNESDAY, APRIL 18

243 Altgeld Hall, 4:00 p.m.
VERTEX ALGEBRA AND ELLIPTIC GENUS
Professor Maarten Bergvelt, Department of Mathematics, UIUC
Vertex algebras and gerbes, IV

114 CSRL, 4:30 p.m.
INFORMATION PROTECTION SEMINAR
Mr. John Jossey
The Cannonical lift of an ordinary elliptic curve over a finite field and its point counting
Abstract: The genesis of the efficient general point counting algorithms for an elliptic curve E over a finite field lies in the work of Schoof. The computational efficiency of the basic Schoof algorithm was imporved by Atkin and Elkies. The techniques of Atkin and Elkies depend on whether the roots of the characteristic equation of the Frobenius map,
\Cal Fl(u) = u2 - tl u+ql = 0
taken modulo a prime l, lie in \Cal Fl or not. This talk will focus on the work of Satoh to count the number of points on an elliptic curve E over a finite field \Cal FpN where p „ 5 and N, a large positive integer. The idea is to lift E to its cannonical lift, which is an elliptic curve over some unramified extension of Qp and compute the trace of the dual of the Frobenius morphism.

The algorithm is easier to implement then the SEA algorithm.

THURSDAY, APRIL 19

ESB 6.110, 12:00 p.m.
MATH - PHYSICS (BCDE) LUNCH SEMINAR
Professor Daniel Grayson, Department of Mathematics, UIUC
Intersection numbers in certain noncommutative algebras

241 Altgeld Hall, 1:00 p.m.
ANALYTIC NUMBER THEORY
Professor Harold Diamond, Department of Mathematics
Oscillation of the counting function of Beurling primes

347 Altgeld Hall, 1:00 p.m.
GROUP THEORY SEMINAR
Professor Alexei Myasnikov, Department of Mathematics, City College of CUNY
On the Tarski conjecture, continued
Abstract: This will be the second lecture in a series of talks on the positive solution (joint with Olga Kharlampovich) to the celebrated Tarski conjecture for free groups. Namely, we will outline the proof that the elementary theory of a finitely generated nonabelian free group is decidable and that any two such groups are elementarily equivalent.

241 Altgeld Hall, 2:00 p.m.
ALGEBRAIC GROUPS AND THEIR REPRESENTATIONS
Frobenius Splitting of Sehubert Cells

243 Altgeld Hall, 2:00 p.m.
ALGEBRAIC NUMBER THEORY
TBA

347 Altgeld Hall, 2:00 p.m.
ANALYSIS SEMINAR
Professor Narcisse Randrianantoanina
Weak type estimate for non-commutative Hilbert-transforms

NOTE: See Special Analysis seminar annoncement for Friday at 4:00 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
Hans-Bjorn Foxby
Evaluation with respect to Modules and Complexes
Abstract: For a given module M we consider the three evaluation morphisms X Æ hom(hom(X,M),M), X Æ hom(M,MŸX)), and X ¨ M Ÿhom(M,X) in the module category as well as their siblings in the derived category. Special examples are Matlis Duality, Hartshorne's Affine Duality, Equivalence with respect to a Dualizing Complex, and Dwyer-Greenlees Equivalence.

347 Altgeld Hall, 3:00 p.m.
GALOIS MODULES
Marcin Mazur, Department of Mathematics, UIUC
The lifted root number conjecture, continued

245 Altgeld Hall, 4:00 p.m.
MATHEMATICS COLLOQUIUM
Yongbin Ruan, Department of Mathematics, University of Wisconsin-Madison
Stringy Geometry and Topology of Orbifolds
Abstract: There is an emerging new subject of mathematics, which we call ``Stringy Geometry and Topology of Orbifold." The motivation of stringy geometry and topology of orbifold comes from orbifold string theory discovered by physicists Dixon, Harvey, Vafa and Witten more than fifteen years ago. Orbifold has been around in mathematics since the 50's. However, the classical theory of orbifold is basically an extension of theory of smooth manifold. The stringy geometry and topology is different. Its main purpose is to study stringy properties of orbifold, which is unique for orbifold. Orbifold string theory model is a popular model in string theory. There are more than two hundred papers on hep-th whose title include orbifold. During the last two years, its mathematical counterpart has undergone rapid development. It is fair to say that new phenomenon is being discovered every month! The growth of its foundation and connections to other areas of mathematics is explosive. In this talk, I will survey the main results on this subject.

Refreshments at 3:15 p.m. in Room 321 Altgeld Hall

FRIDAY, APRIL 20

243 Altgeld Hall, 4:00 p.m.
MODEL THEORY SEMINAR
Professor Anand Pillay, Department of Mathematics, UIUC
Zariski Geometries and Applications

141 Altgeld Hall, 4:00 p.m.
SPECIAL ANALYSIS SEMINAR
Professor Yasuyuki Kawahigashi, from Tokyo University and currently visiting MSRI, Berkeley
Quantum doubles in operator algebra theory