Department of

# Mathematics

Seminar Calendar
for events the day of Wednesday, May 29, 2019.

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Questions regarding events or the calendar should be directed to Tori Corkery.
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30


Wednesday, May 29, 2019

2:00 pm in 243 Altgeld Hall,Wednesday, May 29, 2019

#### Stallings' foldings and cost of treeable equivalence relations (Part 2)

###### Anush Tserunyan (UIUC)

Abstract: Introduced by Levitt and extensively developed by Gaboriau, cost is a very useful real-valued invariant for probability measure preserving countable equivalence relations that measures the infimum amount of edges needed to connect a.e. equivalence class in a uniformly Borel fashion. We discuss Gaboriau's original proof of his Fundamental Theorem of Cost, which states that the cost of a treeable equivalence relation is achieved by any Borel treeing of it.