Department of

# Mathematics

Seminar Calendar
for events the day of Monday, April 8, 2019.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
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Monday, April 8, 2019

1:00 pm in 145 Altgeld Hall,Monday, April 8, 2019

#### Uniform dimension results for the inverse images of symmetric Levy processes.

###### Hyunchul Park (SUNY New Paltz)

Abstract: In this talk, we prove the uniform Hausdorff dimension of the inverse images of a large class of symmetric Levy processes with weak scaling conditions on their characteristic exponents. Along the way we also prove an upper bound for the uniform modulus of continuity of the local times of these processes. This result extends a result of Kaufman (1985) for Brownian motions and of Song, Xiao, and Yang (2018) for stable processes. We also establish the packing dimension results as a byproduct.

3:00 pm in 343 Altgeld Hall,Monday, April 8, 2019

#### Mapping space spectral sequences

###### William Balderrama (UIUC Math)

Abstract: The classical story of obstruction theory for computing maps into a space Y involves lifting maps up the Postnikov tower of Y. In this talk, I will introduce a form of this obstruction theory for computing maps between highly structured objects in homotopy theory. Along the way, we will see why Quillen cohomologies show up in homotopy theory, take derived categories of derived categories, and take multiplicative Postnikov towers of nonconnective ring spectra.

3:00 pm in 243 Altgeld Hall,Monday, April 8, 2019

#### Shifted Poisson structures on differentiable stacks

###### Ping Xu (Pennsylvania State University)

Abstract: We will discuss shifted (+1) Poisson structures on differentiable stacks in terms of Lie groupoids. In particular, we will describe various examples and show their connection with momentum mapping theory in symplectic geometry. This is a joint work with Francesco Bonechi, Nicola Ciccoli, and Camille Laurent-Gengoux.