Recent and upcoming talks by Jan Grebík

Jan Grebík: Borel chromatic numbers

Dear all, The seminar meets on Wednesday July 18th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jan Grebík — Borel chromatic numbers I will present an overview of known facts about Borel chromatic numbers of Borel graphs. continue reading…

Jan Grebik: Applications of topological dynamics to graphons

The seminar meets on Wednesday February 28th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jan Grebik — Applications of topological dynamics to graphons We show that the question about the existence of a Borel or continuous lift for graphons has its counterpart in topological dynamics. continue reading…

Jan Grebik: Borel selector for Hypergraphons

The seminar meets on Wednesday January 3rd at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jan Grebik — Borel selector for Hypergraphons We recall all relevant definitions and show that there is a Borel way of choosing a concrete representant of a hypergraphon. continue reading…

Jan Grebik: Borel selectors of Borel ideals (continued)

Dear all, The seminar meets on Wednesday October 25th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jan Grebik — Borel selectors of Borel ideals (continued) We present a result that there is an F_sigma ideal without Borel selector and deduce that Galvin’s lemma does not have a “Borel proof.” We also show that Nash-Williams theorem has a “Borel proof” and therefore Galvin’s lemma is intrinsically more complex than Nash-Williams theorem. continue reading…

Jan Grebik: Borel selectors of Borel ideals

Dear all, The seminar meets on Wednesday October 18th at 11:00 in the Institute of Mathematics CAS, Zitna 25, seminar room, 3rd floor, front building. Program: Jan Grebik — Borel selectors of Borel ideals We present a result that there is an F_sigma ideal without Borel selector and deduce that Galvin’s lemma does not have a “Borel proof.” We also show that Nash-Williams theorem has a “Borel proof” and therefore Galvin’s lemma is intrinsically more complex than Nash-Williams theorem. continue reading…

Winter School, Jan 28 – Feb 4, 2017

We are pleased to announce that the registration for the Winter School in Abstract Analysis, section Set Theory & Topology is now open. The conference will take place between Jan 28th and Feb 4th 2017 in Hejnice, Czech Republic. continue reading…

Jan Grebik: Oscillations of reals and related forcings

Wednesday, May 20, 2015, 11:00 Prague – IM AS CR, Zitna 25, seminar room, front building, third floor Speaker: Jan Grebik Title: Oscillations of reals and related forcings Abstract: We will review results about oscillations of real numbers and properties of posets defined using oscillations. continue reading…

Jan Grebik: The free sequence number f

Wednesday, March 18, 2015, 11:00 Prague – IM AS CR, Zitna 25, seminar room, front building, third floor Speaker: Jan Grebik (Institute of Mathematics AS CR) Title: The free sequence number f continue reading…

Jan Grebik: The Urysohn space and the Rado graph

Wednesday, January 21, 2015, 11:00 Prague – IM AS CR, Zitna 25, seminar room, front building, third floor Speaker: Jan Grebik Title: The Urysohn space and the Rado graph continue reading…

Jan Grebík, Jan Starý, Egbert Thümmel: TBA

Wednesday, April 30, 2014, 11:00 Prague – CTS Speaker: Jan Grebík, Jan Starý, Egbert Thümmel Title: TBA continue reading…