David Fernández Bretón: All that there is to know about gruff ultrafilters

Wednesday, September 16, 2015

3096 East Hall

16:00-17:30.

Gruff ultrafilters are ultrafilters on the rational numbers that have a basis of perfect sets (according to the usual Euclidean topology). I will explain what is known about their existence, and hopefully (if there’s enough time) finish with a theorem of M. Hrusak and myself that these ultrafilters exist in Miller’s model.

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