BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Okke van Garderen (Max-Planck Institute) DTSTART:20220317T090000Z DTEND:20220317T100000Z DTSTAMP:20260423T004135Z UID:HubEG/1 DESCRIPTION:Title: Sy mmetry & vanishing in the DT theory of cDV singularities\nby Okke van Garderen (Max-Planck Institute) as part of Events Hub: Enumerative geometr y\n\n\nAbstract\nDonaldson–Thomas theory was conceived as a method of co unting certain sheaves in Calabi-Yau threefolds\, which are supposed to en code ‘BPS numbers’ in string theory. More recent developments have led to broader\, refined versions of this theory\, which produce motivic or c ohomological invariants from moduli spaces of semistable objects in the de rived category. In this talk I will focus on DT theory for crepant resolut ions of compound Du-Val singularities\, which include threefold flops\, as well as some divisor-to-curve contractions and quotient singularities. I will explain how one can determine the moduli of semistable objects in thi s setting via a tilting method that is governed by Dynkin diagram combinat orics. Using this\, I will show that the motivic incarnations of the BPS n umbers vanish for K-theory classes outside an associated root lattice\, an d exhibit additional symmetries among these invariants. To make this expli cit\, I will use the example of a dihedral quotient singularity\, for whic h the invariants can be fully calculated.\n\nZoom: 941 5513 6832 Code: YMS C\n LOCATION:https://researchseminars.org/talk/HubEG/1/ END:VEVENT END:VCALENDAR