Seminar Calendar
for events the day of Tuesday, February 7, 2017.

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Questions regarding events or the calendar should be directed to Tori Corkery.
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1  2  3  4  5  6  7             1  2  3  4             1  2  3  4
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Tuesday, February 7, 2017

Geometry, Groups and Dynamics/GEAR Seminar
12:00 pm   in 243 Altgeld Hall,  Tuesday, February 7, 2017
 Del Edit Copy
Submitted by clein.
 Gili Golan (Vanderbilt)The generation problem in Thompson group FAbstract: We show that the generation problem in Thompson group F is decidable, i.e., there is an algorithm which decides if a finite set of elements of F generates the whole F. The algorithm makes use of the Stallings 2-core of subgroups of F, which can be defined in an analogue way to the Stallings core of subgroups of a free group. An application of the algorithm shows that F is a cyclic extension of a group K which has a maximal elementary amenable subgroup B. The group B is a copy of a subgroup of F constructed by Brin and Navas.

Logic Seminar
1:00 pm   in 345 Altgeld Hall,  Tuesday, February 7, 2017
 Del Edit Copy
Submitted by anush.
 Canceled

Graph Theory and Combinatorics Seminar
3:00 pm   in 241 Altgeld Hall,  Tuesday, February 7, 2017
 Del Edit Copy
Submitted by molla.
 Ruth Luo (Illinois Math)The maximum number of cliques in graphs without long cyclesAbstract: The Erdős-Gallai Theorem states that for $k\geq 3$ every graph on $n$ vertices with more than $\frac{1}{2}(k-1)(n-1)$ edges contains a cycle of length at least $k$. Kopylov proved a strengthening of this result for 2-connected graphs with extremal examples $H_{n,k,t}$ and $H_{n,k,2}$. In this talk, we generalize the result of Kopylov to bound the number of $s$-cliques in a graph with circumference less than $k$. Furthermore, we show that the same extremal examples that maximize the number of edges also maximize the number of cliques of any fixed size. Finally, we obtain the extremal number of $s$-cliques in a graph with no path on $k$-vertices.