BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Olivier Schiffmann (Université de Paris-Sud ORSAY) DTSTART:20210317T200000Z DTEND:20210317T210000Z DTSTAMP:20260414T173652Z UID:BUGeom/19 DESCRIPTION:Title: Cohomological Hall algebras\, Yangians and Kleinian surface singularities< /a>\nby Olivier Schiffmann (Université de Paris-Sud ORSAY) as part of Bos ton University Geometry/Physics Seminar\n\nLecture held in Zoom meeting ID : 974 5641 9902.\n\nAbstract\nModuli spaces of sheaves on complex surfaces play an important role in algebraic geometry\, with motivation coming fro m (among others) string theory and gauge theory.\n\nOne way to understand the structure of the cohomology of such moduli spaces is to construct an a ction of a suitable algebra\, through some 'Hecke type' correspondences. T raditionally\, one considers Hecke correspondences modifying a sheaf at a single point (varying along a fixed cycle on the surface). In an ongoing j oint work with Diaconescu\, Sala and Vasserot\, we consider the case of re solutions of Kleinian singularities\, and modifications along the (1-dimen sional) components of the exceptional locus. This yields actions of some Y angian type algebras (more precisely\, affine Yangians). The main tool is the notion of cohomological Hall algebra\, and the main technical result d escribes the behavior of such algebras upon derived equivalences coming fr om reflection functors.\n LOCATION:https://researchseminars.org/talk/BUGeom/19/ END:VEVENT END:VCALENDAR