BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Nikolas Kuhn (Stanford University) DTSTART:20210326T190000Z DTEND:20210326T200000Z DTSTAMP:20260407T231600Z UID:agstanford/44 DESCRIPTION:Title: A blowup formula for virtual Donaldson invariants\nby Nikolas Kuhn (Stanford University) as part of Stanford algebraic geometry seminar\n\n\ nAbstract\nDonaldson invariants were a breakthrough in the study of smooth four-manifolds when they were introduced in the 1980s and even found appl ications to the classification of compact complex surfaces. With the adven t of the virtual fundamental class\, it has become possible to give an ele gant purely algebraic definition when working on a complex projective surf ace X\, which was done by T. Mochizuki. The two definitions agree in most cases\, and whether they agree in general comes down to knowing a blowup f ormula for Mochizuki's invariants. We present a direct proof of such a blo wup formula that generalizes earlier results by Göttsche-Nakajima-Yoshiok a and has applications to other types of enumerative invariants of X. This is joint work with Yuuji Tanaka.\n\nThe discussion for Nikolas Kuhn’s t alk is taking place not in zoom-chat\, but at https://tinyurl.com/2021-03- 26-nk (and will be deleted after ~3-7 days).\n LOCATION:https://researchseminars.org/talk/agstanford/44/ END:VEVENT END:VCALENDAR