Department of

# Mathematics

Seminar Calendar
for events the day of Monday, November 9, 2015.

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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, November 9, 2015

4:00 pm in 141 Altgeld Hall,Monday, November 9, 2015

#### No talk scheduled

4:00 pm in 245 Altgeld Hall,Monday, November 9, 2015

#### Color-critical graphs with few edges

###### Alexandr Kostochka (Department of Mathematics, University of Illinois)

Abstract: A (proper) k-coloring of a graph G is an assignment of colors 1,2,...,k to the vertices of G such that the ends of each edge get distinct colors. A graph is k-critical if it does not have a (k-1)-coloring, but each its proper subgraph has. We discuss the problem of finding the sparsest k-critical graphs and describe some recent progress on it. The talk is based on joint results with Matthew Yancey, who graduated from Illinois in 2013.

4:00 pm in 145 Altgeld Hall,Monday, November 9, 2015

#### Enumerative Geometry via Localization

###### Joseph Pruitt (UIUC Math)

Abstract: During this talk we will discuss how to solve problems in Enumerative Geometry using the localization theorem of Atiyah and Bott. We will begin by defining equivariant cohomlogy leading to the statement of the localization theorem. Then we will explore equivariant cohomolgy in projective space and, by extending our notions to smooth stacks, will show how to answer questions in enumerative geometry with relatively simple computations.

5:00 pm in 241 Altgeld Hall,Monday, November 9, 2015

#### Pointwise Ergodic Theorem for a class of groups

###### Anthony Sanchez (UIUC Math)

Abstract: We prove the Pointwise Ergodic theorem for amenable group actions that are equipped with a right-invariant proper metric and a doubling measure.