Department of

# Mathematics

Seminar Calendar
for events the day of Thursday, February 9, 2006.

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Questions regarding events or the calendar should be directed to Tori Corkery.
     January 2006          February 2006            March 2006
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1  2  3  4  5  6  7             1  2  3  4             1  2  3  4
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Thursday, February 9, 2006

12:00 pm in 464 Loomis,Thursday, February 9, 2006

#### The A-model as a Thom Form

###### Josh Guffin (UIUC Physics)

Abstract: I will show that the A-model path integral is a representative of the Thom form of a certain infinite dimensional vector bundle on MAP(\Sigma,X). I will also prove that the path integral localizes to holomorphic maps.

1:00 pm in 347 Altgeld Hall,Thursday, February 9, 2006

#### Uniform convergence groups and the mapping class group.II

###### Chris Leininger (UIUC Math)

Abstract: Abstract: I'll go through the proof that a non-elementary subgroup of Mod(S) is convex cocompact if and only if it acts as a uniform convergence group on the zero locus of its limit set. This is joint work with Richard Kent.

1:00 pm in 241 Altgeld Hall,Thursday, February 9, 2006

#### Shards of proofiness about the Stern sequence

###### Bruce Reznick (UIUC Math )

Abstract: Isaac Stern was a serious violinist. Howard Stern is on Sirius radio. The Stern sequence is a hilariously interesting mathematical object, defined recursively by s(0) = 0, s(1) = 1, s(2n) = s(n), s(2n+1) = s(n) + s(n+1). We will present some hysterical recent results, taken from the speaker's ongoing course Math 595 SNT

2:00 pm in 443 Altgeld Hall,Thursday, February 9, 2006

#### Exotic 7-spheres

###### David Lispky (UIUC Math)

Abstract: I will present Milnor's paper "On Manifolds Homeomorphic to the 7-Sphere." In this paper, Milnor defines a diffeomorphism invariant "lambda" for certain smooth 7-dimensional manifolds. He then constructs, for each integer k, a smooth manifold M_k homeomorphic to the 7-sphere. Amazingly enough, lambda(M_k) varies with k, which means that homeomorphic smooth manifolds need not be diffeomorphic. In particular, there exist several distinct smooth structures on the 7-sphere. I will cover some background material and the beginning of Milnor's construction this week, and will continue next week if needed.

2:00 pm in 241 Altgeld Hall,Thursday, February 9, 2006

#### Realization of Nilpotent Groups with Restricted Ramification

###### Nadya Markin (UIUC Math)

3:00 pm in 345 Altgeld Hall,Thursday, February 9, 2006

#### On the Estimates of the Density of the Feynman-Kac Semigroups of alpha-Stable-like Processes

###### Chunlin Wang (UIUC Math)

Abstract: Suppose that alpha is between 0 and 2 and that X is an alpha-stable-like process on R^d. Let F be a function on R^d belonging to the class J_{d,alpha} and B^F_{t} be the discontinuous additive functional of X. With F not symmetric or X not symmetric, under certain conditions, we show that the density of the Feynman-Kac semigroup introduced by B^F_{t} has a density which is comparable to that of the alpha-stable-like process.