BEGIN:VCALENDAR VERSION:2.0 PRODID:-//132.216.98.100//NONSGML kigkonsult.se iCalcreator 2.20.4// BEGIN:VEVENT UID:20251121T140807EST-46082pgZZ4@132.216.98.100 DTSTAMP:20251121T190807Z DESCRIPTION: \n\nSeminar Geometric Group Theory\n  \n\nNew bounds for `homot opical Ramsey theory' on surfaces\n \n Farb and Leininger asked: How many di stinct (isotopy classes of) simple closed curves on a finite-type surface S may pairwise intersect at most k times? Przytycki has shown that this nu mber grows at most as a polynomial in |χ(S)| of degree k^2+k+1. We present narrowed bounds by showing that the above quantity grows slower than |χ(S )|^{3k}. The most interesting case is that of k=1\, in which case the size of a `maximal 1-system' grows sub-cubically in |χ(S)|. Following Przytyck i\, the proof uses the hyperbolic geometry of a surface of negative Euler characteristic essentially. In particular\, we require bounds for the maxi mum size of a collection of curves of length at most L on a hyperbolic sur face homeomorphic to S of the form F(L)·|χ|\, a point of view that yields intriguing questions in its own right. This is joint work with Tarik Aouga b and Ian Biringer.\n\n \n\nWeb site : http://www.math.mcgill.ca/ggt/\n DTSTART:20170405T190000Z DTEND:20170405T190000Z LOCATION:BURN 920\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue Sherbrooke Ouest SUMMARY:Jonah Gaster\, Boston College URL:/mathstat/channels/event/jonah-gaster-boston-colle ge-267429 END:VEVENT END:VCALENDAR