BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Julie Desjardins (University of Toronto) DTSTART:20221117T210000Z DTEND:20221117T220000Z DTSTAMP:20260423T021030Z UID:NTC/3 DESCRIPTION:Title: Tors ion points and concurrent lines on Del Pezzo surfaces of degree one\nb y Julie Desjardins (University of Toronto) as part of Lethbridge number th eory and combinatorics seminar\n\n\nAbstract\nThe blow up of the anticanon ical base point on X\, a del Pezzo surface of degree 1\, gives rise to a r ational elliptic surface E with only irreducible fibers. The sections of m inimal height of E are in correspondence with the 240 exceptional curves o n X. A natural question arises when studying the configuration of those cu rves : \n\nIf a point of X is contained in "many" exceptional curves\, is it torsion on its fiber on E?\n\nIn 2005\, Kuwata proved for del Pezzo sur faces of degree 2 (where there is 56 exceptional curves) that if "many" eq uals 4 or more\, then yes. In a joint paper with Rosa Winter\, we prove th at for del Pezzo surfaces of degree 1\, if "many" equals 9 or more\, then yes. Moreover\, we find counterexamples where a torsion point lies at the intersection of 7 exceptional curves.\n LOCATION:https://researchseminars.org/talk/NTC/3/ END:VEVENT END:VCALENDAR