Symmetry in Newcastle seminar is here again!!
Feel free to grab a beverage appropriate for your respective timezone and join us for a friendly chat during the break!
The talks will be recorded and made available on our YouTube channel https://tinyurl.com/zerodimensionalgroup and our website https://zerodimensional.group/. The running times of the talks, titles and abstracts are as follows
Time: 17:30–18:30 AEDT (06:30–07:30 UTC) Sanghyun Kim
18:30–19:00 AEDT (07:30–08:00 UTC) Break and chat
Time: 19:00–20:00 AEDT (08:00–09:00 UTC) Francois Thilmany
Speaker: Sanghyun Kim
Title: Optimal regularity of mapping class group actions on the circle
Abstract: We prove that for each finite index subgroup H of the mapping class group of a closed hyperbolic surface, and for each real number r>0 there does not exist a faithful C 1+r-action of H on a circle. (Joint with Thomas Koberda and Cristobal Rivas)
Speaker: Francois Thilmany
Title: Uniform discreteness of arithmetic groups and the Lehmer conjecture
Abstract: The famous Lehmer problem asks whether there is a gap between 1 and the Mahler measure of algebraic integers which are not roots of unity. Asked in 1933, this deep question concerning number theory has since then been connected to several other subjects. After introducing the concepts involved, we will briefly describe a few of these connections with the theory of linear groups. Then, we will discuss the equivalence of a weak form of the Lehmer conjecture and ‘uniform discreteness’ of cocompact lattices in semisimple Lie groups (conjectured by Margulis). Joint work with Lam Pham.
The zoom link is https://uonewcastle.zoom.us/j/82596235512.
Hope to see some of you on Monday!