Tel Aviv University Dear all, Next week will be the final meeting for the semester of the Horowitz seminar on Probability, Ergodic Theory and Dynamical Systems at Tel Aviv University. We are happy to have: Speaker: Pascal Vanier, Hebrew University Title: Characterizations of periods of multidimensional SFTs Date: Monday, June 24 Time: 14:30 Place: Schreiber 309 Abstract: In this talk, we will introduce several notions of periodicity for higher dimensional shifts and give computational characterizations of sets of periods of SFTs for some of them. We will in particular focus on points with a finite orbit, the straightforward generalization of periodicity from dimension 1. We will show that sets of periods of multidimensional SFTs correspond exactly to the languages of the computational complexity class NE (languages recognizable in nondeterministic linear exponential time). In order to attain this result we will first focus on the intermediate notion of horizontal periodicity, whose characterization is easier to achieve. Best regards, Ron Seminar webpage: <http://www.math.tau.ac.il/~peledron/Horowitz_seminar/Horowitz_seminar.html> --------------------------------------------------------- Technion Math Net-2 (TECHMATH2) Editor: Michael Cwikel <techm@math.technion.ac.il> Announcement from: Ron Peled <peledron@post.tau.ac.il>