Seminar Calendar
for events the day of Tuesday, September 14, 2010.

.
events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
     August 2010           September 2010          October 2010
Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa
1  2  3  4  5  6  7             1  2  3  4                   1  2
8  9 10 11 12 13 14    5  6  7  8  9 10 11    3  4  5  6  7  8  9
15 16 17 18 19 20 21   12 13 14 15 16 17 18   10 11 12 13 14 15 16
22 23 24 25 26 27 28   19 20 21 22 23 24 25   17 18 19 20 21 22 23
29 30 31               26 27 28 29 30         24 25 26 27 28 29 30
31


Tuesday, September 14, 2010

Topology Seminar
11:00 am   in 241 Altgeld Hall,  Tuesday, September 14, 2010
 Del Edit Copy
Submitted by rezk.
 Charles Rezk (UIUC Math)Subgroups of elliptic curvesAbstract: I will talk about the moduli of subgroups of elliptic curves, following the treatment of Katz-Mazur. Then I'll describe some interesting relationships between the moduli of subgroups of various kinds; if time permits, I'll talk about what this has to do with algebraic topology.

Number Theory
1:00 pm   in 241 Altgeld Hall,  Tuesday, September 14, 2010
 Del Edit Copy
Submitted by berndt.
 Harold Diamond (UIUC)Two Results on Beurling Generalized NumbersAbstract: A sequence of Beurling generalized primes (g-primes) is an increasing, unbounded sequence of numbers exceeding 1. The semigroup it generates under multiplication is called the associated sequence of g-integers. No additive structure is assumed for g-integers. A survey will be given of two major theorems in the area: Kahane's L^2 proof of the prime number theorem and the DMV oscillation theorem.

Logic seminar
1:00 pm   in Altgeld Hall 345,  Tuesday, September 14, 2010
 Del Edit Copy
Submitted by vddries.
 Lou van den Dries (UIUC Math)The o-minimal HauptvermutungAbstract: This is the first of several talks on Shiota's proof of the o-minimal Hauptvermutung which he has circulated in a preprint. This first talk will discuss the general background. The second talk will be on Friday September 17.

2:00 pm   in 345 Altgeld Hall,  Tuesday, September 14, 2010
 Del Edit Copy
Submitted by lukyane2.
 Nat Stapleton (UIUC)Stacks and DescentAbstract: We will motivate the definition of a stack providing all of the necessary prerequisites. We will also discuss several examples and generalizations.

Study Seminar in Analysis and Geometry
3:00 pm   in 347 Altgeld Hall,  Tuesday, September 14, 2010
 Del Edit Copy
Submitted by jmmackay.
 John Mackay (Department of Mathematics, University of Illinois)The Heisenberg group does not admit a bi-Lipschitz embedding into L^1Abstract: We will discuss the recent result of Cheeger and Kleiner which shows that the Heisenberg group (with its natural Carnot-Caratheodory metric) does not admit a bi-Lipschitz embedding into the Banach space L^1. (This result gives a natural counterexample to the Goemans-Linial conjecture regarding the Sparsest Cut problem in computer science.) The proof involves ideas including: differentiation with Banach space targets, cut metrics, and the geometry of the Heisenberg group. All these notions will be defined and explained. [This seminar meets from 3-4:50 with a break halfway when you can escape.]

Graph Theory and Combinatorics
3:00 pm   in 241 Altgeld Hall,  Tuesday, September 14, 2010
 Del Edit Copy
Submitted by west.
 Hehui Wu (UIUC Math)Decomposition of sparse graphs into forests and a graph with bounded degreeAbstract: For d≥k+1, we prove a sharp sparseness condition for decomposability into k forests and a graph having maximum degree at most d. Consequences include that every graph with fractional arboricity at most k+d/(k+d+1) has such a decomposition. For d≤k+1, we prove that every graph with fractional arboricity at most k+d/(2k+2) decomposes into k+1 forests having maximum degree at most d. This result implies the Nine Dragon Tree (NDT) Conjecture for the case k=d+1. This is joint work with Seog-jin Kim, Alexandr V. Kostochka, Douglas B. West, and Xuding Zhu.