BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Forrest Glebe (University of Hawai'i\, Mānoa) DTSTART:20251105T200000Z DTEND:20251105T210000Z DTSTAMP:20260420T053103Z UID:NYC-NCG/210 DESCRIPTION:Title: Characters of Bundles Associated to Almost Representations of Discrete G roups\nby Forrest Glebe (University of Hawai'i\, Mānoa) as part of No ncommutative geometry in NYC\n\n\nAbstract\nA group is said to be matricia lly stable if every function from the group to unitary matrices that is "a lmost multiplicative" in the point-operator norm topology is "close\," in the same topology\, to a genuine representation. A result of Dadarlat show s that even cohomology obstructs matricial stability. The obstruction in h is proof can be realized as follows. To each almost-representation\, we ma y associate a vector bundle. This vector bundle has topological invariants \, called Chern characters\, which lie in the even cohomology of the group . If any of these invariants are nonzero\, the almost-representation is fa r from a genuine representation. The first Chern character can be computed with the "winding number argument" of Kazhdan\, Exel\, and Loring\, but t he other invariants are harder to compute explicitly. In this talk\, I wil l discuss results that allow us to compute higher invariants in specific c ases: when the failure to be multiplicative is scalar (joint work with Mar ius Dadarlat) and when the failure to be multiplicative is small in a Scha tten p-norm.\n LOCATION:https://researchseminars.org/talk/NYC-NCG/210/ END:VEVENT END:VCALENDAR