BEGIN:VCALENDAR
VERSION:2.0
PRODID:icalendar-ruby
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VTIMEZONE
TZID:Europe/Vienna
BEGIN:DAYLIGHT
DTSTART:20250330T030000
TZOFFSETFROM:+0100
TZOFFSETTO:+0200
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
TZNAME:CEST
END:DAYLIGHT
BEGIN:STANDARD
DTSTART:20251026T020000
TZOFFSETFROM:+0200
TZOFFSETTO:+0100
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZNAME:CET
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTAMP:20260424T143213Z
UID:648ae47527db5956311754@ist.ac.at
DTSTART:20250410T130000
DTEND:20250410T150000
DESCRIPTION:Speaker: Lucien Hennecart\nhosted by Tamas Hausel / Tanguy Vern
 et\nAbstract: In this talk\, I will explain the notion of cohomological in
 tegrality\, originally introduced by Kontsevich and Soibelman in the conte
 xt of quiver representations\, and which has then been extended to a broad
 er range of settings\, including sheaves on K3 surfaces and\, more general
 ly\, 2- and 3-Calabi-Yau categories. My focus will be on extending these r
 esults to the setting of quotient stacks arising from representations of r
 eductive groups and\, more broadly\, smooth affine algebraic varieties und
 er the action of a reductive group. The main result is a decomposition of 
 the cohomology of the corresponding quotient stack (which is usually infin
 ite-dimensional) into finitely many pieces involving finite-dimensional su
 bspaces. The objective is to define and understand enumerative invariants 
 associated with the corresponding Geometric Invariant Theory (GIT) quotien
 ts. I will present the core representation-theoretic results that underlie
  these constructions and discuss the application to the proof of a purity 
 conjecture of Halpern-Leistner for derived stacks with self-dual cotangent
  complex. I will also mention the link with the intersection cohomology of
  the affine GIT quotient\, following independent and recent work of Bu\, D
 avison\, Ibanez Nunez\, Kinjo and Padurariu.
LOCATION:Office Bldg West / Ground floor / Heinzel Seminar Room (I21.EG.101
 )\, ISTA
ORGANIZER:boosthui@ist.ac.at
SUMMARY:Lucien Hennecart: Cohomological integrality for quotient stacks
URL:https://talks-calendar.ista.ac.at/events/5519
END:VEVENT
END:VCALENDAR