BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Diego Martínez (ICMAT - Institute of Mathematical Sciences) DTSTART:20200506T103000Z DTEND:20200506T113000Z DTSTAMP:20260423T011111Z UID:YSseminar/1 DESCRIPTION:Title: Some quasi-isometric invariants for inverse semigroups\nby Diego Mar tínez (ICMAT - Institute of Mathematical Sciences) as part of York semigr oup seminar\n\n\nAbstract\nCoarse geometry is the study of metric spaces f rom a point of view far away\, that is\, up to coarse equivalence. Possibl y the most studied factory of examples are finitely generated groups\, whi ch are naturally equipped with the path length metric of their Cayley grap hs. One can then move onto the context of inverse semigroups where\, for v arious reasons we will detail\, one has to study its Schützenberger graph s. Properties of the semigroup that are invariant under coarse equivalence \, such as the growth type and the number of ends\, are here of particular interest.\n\nIn this talk we will be interested in two other properties\, namely amenability and property A. Amenability was introduced by Day in 1 957 as the existence of an invariant measure of the semigroup\, but it can be characterized from a geometric point of view in the Schützenberger gr aphs of the semigroup. Viewed from this point of view\, we will derive a c ertain necessary condition and prove that it's a quasi-isometric invariant . Much more recent is property A. In the talk we will define it and discus s its uses and possible characterizations\, mostly in relation with C*-alg ebras.\n\nThis is based on joint work with Fernando Lledó and Pere Ara.\n LOCATION:https://researchseminars.org/talk/YSseminar/1/ END:VEVENT END:VCALENDAR