BEGIN:VCALENDAR VERSION:2.0 PRODID:-//132.216.98.100//NONSGML kigkonsult.se iCalcreator 2.20.4// BEGIN:VEVENT UID:20250807T172118EDT-1461un7Evn@132.216.98.100 DTSTAMP:20250807T212118Z DESCRIPTION:Title: Shi arrangements in Coxeter groups\n\nAbstract: Given an arbitrary Coxeter system (W\,S) and a nonnegative integer m\, the m-Shi a rrangement of (W\, S) is a subarrangement of the Coxeter hyperplane arrang ement of (W\,S). The classical Shi arrangement (m = 0) was introduced in t he case of affine Weyl groups by Shi to study Kazhdan-Lusztig cells for W. As two key results\, Shi showed that each region of the Shi arrangement c ontains exactly one element of minimal length in W and that the union of t heir inverses form a convex subset of the Coxeter complex. The set of m-lo w elements in W were introduced to study the word problem of the correspon ding Artin-Tits (braid) group and they turn out to produce automata to stu dy the combinatorics of reduced words in W. In this talk\, I will discuss how to Shi’s results extend to any Coxeter system and show that the minima l elements in each Shi region are in fact the m-low elements. This talk is based on joint work with Matthew Dyer\, Susanna Fishel and Alice Mark.\n \nWe will gather for teatime in the lounge after the talk.\n\n \n DTSTART:20250205T210000Z DTEND:20250205T220000Z LOCATION:Room 920\, Burnside Hall\, CA\, QC\, Montreal\, H3A 0B9\, 805 rue Sherbrooke Ouest SUMMARY:Christophe Hohlweg (UQAM) URL:/mathstat/channels/event/christophe-hohlweg-uqam-3 63053 END:VEVENT END:VCALENDAR