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Logic Seminar

Wednesday, May 10, 2023
12:00pm to 1:00pm
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Online Event
Every CBER is smooth below the Carlson-Simpson generic partition
Allison Wang, Department of Mathematical Sciences, Carnegie Mellon University,

Please note that the time is PST

One difficulty that arises in studying the class of countable Borel equivalence relations (CBERs) is that in many cases, the complexity of a CBER lies on a "small" set. For instance, a result of Hjorth and Kechris states that every CBER on a Polish space is hyperfinite when restricted to some comeager set. Another result, due to Mathias, shows that every CBER on the Ellentuck Ramsey space is hyperfinite when restricted to some pure Ellentuck cube. In this talk, we will show that every CBER on the space of all infinite partitions of the natural numbers coincides with equality below a Carlson-Simpson generic element. This is joint work with Aristotelis Panagiotopoulos.

For more information, please contact Math Dept. by phone at 626-395-4335 or by email at A. Kechris at [email protected].