BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Carl-Fredrik Nyberg Brodda (Kias) DTSTART:20260922T130000Z DTEND:20260922T140000Z DTSTAMP:20261006T044749Z UID:UEAPS/79 DESCRIPTION:Title: P rofinite non-rigidity of braid groups and free-by-cyclic groups\nby Ca rl-Fredrik Nyberg Brodda (Kias) as part of ANTLR seminar\n\nLecture held i n C.HALL 01.10.\n\nAbstract\nWhen is a finitely generated algebraic object determined by its finite quotients? This is the core question underlying profinite rigidity. I will give an introduction to some of the key ideas b ehind profinite rigidity\, and discuss some recent results concerning the non-rigidity of some groups. In particular\, I will show that braid groups are not profinitely rigid\, giving the first known examples of profinitel y non-rigid mapping class groups. I will also give a brief overview of a r ecent result that free-by-cyclic groups are not relatively profinitely rig id\, which answered a question of Bridson & Reid from 2015. Time permittin g I will also discuss what happens in the semigroup setting\, especially f or free semigroups.\n LOCATION:https://researchseminars.org/talk/UEAPS/79/ END:VEVENT END:VCALENDAR