BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Raymond Cheng (Columbia University) DTSTART:20211028T223000Z DTEND:20211028T233000Z DTSTAMP:20260422T054030Z UID:SFUQNTAG/40 DESCRIPTION:Title: Unbounded negativity on rational surfaces in positive characteristic \nby Raymond Cheng (Columbia University) as part of SFU NT-AG seminar\n\n\ nAbstract\nFix your favourite smooth projective surface S and wonder: how negative can the self-intersection of a curve in S be? Apparently\, there are situations in which curves might not actually get so negative: an old folklore conjecture\, nowadays known as the Bounded Negativity Conjecture\ , predicts that if S were defined over the complex numbers\, then the self -intersection of any curve in S is bounded below by a constant depending o nly on S. If\, however\, S were defined over a field of positive character istic\, then it is known that the Bounded Negativity Conjecture as stated cannot hold. For a long time\, however\, it was not known whether the Conj ecture failed for rational surfaces in positive characteristic. In this ta lk\, I describe the first examples of rational surfaces failing Bounded Ne gativity which I constructed with Remy van Dobben de Bruyn earlier this ye ar.\n LOCATION:https://researchseminars.org/talk/SFUQNTAG/40/ END:VEVENT END:VCALENDAR