BEGIN:VCALENDAR VERSION:2.0 PRODID:-//132.216.98.100//NONSGML kigkonsult.se iCalcreator 2.20.4// BEGIN:VEVENT UID:20251120T091705EST-1052zvIld0@132.216.98.100 DTSTAMP:20251120T141705Z DESCRIPTION:Title: Arboreal structures on groups and the associated boundar ies - III\n\nAbstract: Geometers are very much used to endowing manifolds with additional structures (Riemannian\, symplectic\, etc.). Likewise\, a group can be equipped with a probability measure which gives rise to the a ssociated random walk (in the same way as a Riemannian metric gives rise t o the associated Brownian motion). This setup produces the Poisson boundar y as a measure space which describes the stochastically significant behavi our of the sample paths of the random walk at infinity.\n \n The Poisson bou ndary can usually be identified with the natural geometric boundary of the group (provided the latter is well-defined) endowed with an appropriate h itting distribution (e.g.\, for hyperbolic groups\, cf. the classical Pois son formula for the hyperbolic plane in the disk model). Still\, a number of very natural questions about the identification of the Poisson boundary (or even just about its non-triviality) for general groups remain wide op en. It has been known for nearly 40 years that amenable groups can be char acterized as the ones for which there *exists* a measure with the trivial Poisson boundary. According to a very recent result of Frisch - Hartman - Tamuz - Vahidi Ferdowsi the hyper-FC-central groups are precisely those fo r which the boundary of *any* measure is trivial. The key ingredient of th is result is the existence of a measure with a non-trivial boundary on any group with infinite conjugacy classes (ICC). I will talk about a joint wo rk with Anna Erschler\, in which we introduce a new arboreal structure on an arbitrary ICC group and subsequently identify the Poisson boundary in t erms of this structure.\n DTSTART:20190426T180000Z DTEND:20190426T190000Z LOCATION:Room 4336\, CA\, Pav. André-Aisenstadt SUMMARY:Vadim Kaimanovich\, Université d'Ottawa URL:/mathstat/channels/event/vadim-kaimanovich-univers ite-dottawa-296384 END:VEVENT END:VCALENDAR