BEGIN:VCALENDAR VERSION:2.0 PRODID:-//132.216.98.100//NONSGML kigkonsult.se iCalcreator 2.20.4// BEGIN:VEVENT UID:20260620T193016EDT-5392wf5AOV@132.216.98.100 DTSTAMP:20260620T233016Z DESCRIPTION:Title: Torsion groups do not act on 2-dimensional CAT(0) comple xes.\n\nAbstract: We show\, under mild hypotheses\, that if each element o f a finitely generated group acting on a 2-dimensional CAT(0) complex has a fixed point\, then the action is trivial. In particular\, all actions of finitely generated torsion groups on such complexes are trivial. As an in gredient\, we prove that the image of an immersed loop in a graph of girth 2Ï€ with length not commensurable to Ï€ has diameter >Ï€. This is related to a theorem of Dehn on tiling rectangles by squares. Joint work with Sergey Norin and Damian Osajda.\n DTSTART:20190313T190000Z DTEND:20190313T200000Z LOCATION:Room 920\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue Sherbrooke Ouest SUMMARY:Piotr Przytycki (91ºÚÁÏÍø) URL:/mathstat/channels/event/piotr-przytycki-mcgill-un iversity-295340 END:VEVENT END:VCALENDAR