BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Ed Segal (University College London) DTSTART:20200708T123000Z DTEND:20200708T133000Z DTSTAMP:20260423T005802Z UID:notts_ag/14 DESCRIPTION:Title: Semi-orthogonal decompositions and discriminants\nby Ed Segal (Unive rsity College London) as part of Online Nottingham algebraic geometry semi nar\n\n\nAbstract\nThe derived category of a toric variety can usually be decomposed into smaller pieces\, by passing through different birational m odels and applying the "windows" theory relating VGIT and derived categori es. There are many choices involved and the decompositions are not unique. We prove a Jordan-Hölder result\, that the multiplicities of the pieces are independent of choices. If the toric variety is Calabi-Yau then there are no decompositions\, instead the theory produces symmetries of the deri ved category. Physics predicts that these all these symmetries form an act ion of the fundamental group of the "FI parameter space". I'll explain why our Jordan-Hölder result is necessary for this prediction to work\, and state a conjecture (based on earlier work of Aspinwall-Plesser-Wang) relat ing our multiplicities to the geometry of the FI parameter space. This is joint work with Alex Kite.\n LOCATION:https://researchseminars.org/talk/notts_ag/14/ END:VEVENT END:VCALENDAR