Department of

# Mathematics

Seminar Calendar
for events the day of Friday, November 8, 2013.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
     October 2013          November 2013          December 2013
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                   1  2    1  2  3  4  5  6  7
6  7  8  9 10 11 12    3  4  5  6  7  8  9    8  9 10 11 12 13 14
13 14 15 16 17 18 19   10 11 12 13 14 15 16   15 16 17 18 19 20 21
20 21 22 23 24 25 26   17 18 19 20 21 22 23   22 23 24 25 26 27 28
27 28 29 30 31         24 25 26 27 28 29 30   29 30 31



Friday, November 8, 2013

4:00 pm in 345 Altgeld Hall,Friday, November 8, 2013

#### Approximate groups [after Hrushovski and Breuillard, Green, Tao]

###### Lou van den Dries (UIUC)

Abstract: Given a group G, a symmetric subset X containing the identity is said to be a K-approximate group if XX can be covered by at most K translates gX. Here K is a positive integer. The main result describes a finite K-approximate group as being essentially finite-by-nilpotent. (This is a rehearsal for my Bourbaki seminar talk on November 16.)

4:00 pm in 241 Altgeld Hall,Friday, November 8, 2013

#### Toric Geometry and Coxeter Arrangements

###### Nathan Fieldsteel (UIUC Math)

Abstract: To any hyperplane arrangement we can naturally associate two different toric varieties, one described by the sectors into which the arrangement partitions the ambient space, and the other described by the combinatorial intersection data of the arrangement. In the event that the reflection arrangement of a Coxeter group, there should be a close relationship between these two toric varieties. In this talk, we will cover the necessary background, provide some motivation, and discuss progress towards an explicit description of this relation.