Events for 01/15/2025 from all calendars
Groups and Dynamics Seminar
Time: 3:00PM - 4:00PM
Location: BLOC 628
Speaker: Volodymyr Nekrashevych, Texas A&M University
Title: Penrose tiling, semigroups, and ample groups.
Abstract: We will discuss the Penrose tiling (like the one found in the Mitchell Physics Building), its definition, and basic properties. We will introduce a natural groupoid acting on the space of marked tilings and the associated inverse semigroup following J. Kellendonk. We will see that this inverse semigroup has a natural contracting self-similarity and is generated by a finite automaton. The topological full group (ample group) of this semigroup (the group of pattern-equivariant permutations of the tiles) has a nice interpretation as a group of rearrangements of the golden triangle. We will see how this interpretation is related to an Anosov automorphism of a 4-dimensional orbifold, and discuss some properties of the full group.
Arthur Jaffe - Hagler Fellow
Time: 4:00PM - 5:00PM
Location: Bloc 117
Speaker: CANCELLED: Arthur Jaffe, Hagler Fellow
Description: CANCELLED: Title: Is relativity compatible with quantum theory? Abstract: What is the history of the problem? What is understood? What is the fundamental open question?