Jörg Thuswaldner: S-adic sequences: a bridge between dynamics, arithmetic, and geometry скачать в хорошем качестве

Jörg Thuswaldner: S-adic sequences: a bridge between dynamics, arithmetic, and geometry

Abstract: Based on work done by Morse and Hedlund (1940) it was observed by Arnoux and Rauzy (1991) that the classical continued fraction algorithm provides a surprising link between arithmetic and diophantine properties of an irrational number αα, the rotation by αα on the torus 𝕋=ℝ/ℤT=R/Z, and combinatorial properties of the well known Sturmian sequences, a class of sequences on two letters with low subword complexity. It has been conjectured since the early 1990ies that this correspondence carries over to generalized continued fraction algorithms, rotations on higher dimensional tori, and so-called SS-adic sequences generated by substitutions. The idea of working towards this generalization is known as Rauzy's program. Although, starting with Rauzy (1982) a number of examples for such a generalization was devised, Cassaigne, Ferenczi, and Zamboni (2000) came up with a counterexample that showed the limitations of such a generalization. Nevertheless, recently Berthé, Steiner, and Thuswaldner (2016) made some further progress on Rauzy's program and were able to set up a generalization of the above correspondences. They proved that the above conjecture is true under certain natural conditions. A prominent role in this generalization is played by tilings induced by generalizations of the classical Rauzy fractal introduced by Rauzy (1982). Another idea which is related to the above results goes back to Artin (1924), who observed that the classical continued fraction algorithm and its natural extension can be viewed as a Poincaré section of the geodesic flow on the space SL2(ℤ) SL2(ℝ)SL2(Z) SL2(R). Arnoux and Fisher (2001) revisited Artin's idea and showed that the above mentioned correspondence between continued fractions, rotations, and Sturmian sequences can be interpreted in a very nice way in terms of an extension of this geodesic flow which they called the scenery flow. Currently, Arnoux et al. are setting up elements of a generalization of this connection as well. It is the aim of my series of lectures to review the above results. Recording during the Jean-Morlet chair research school "Tiling Dynamical System" the November 21, 2017 at the Centre International de Rencontres Mathématiques (Marseille, France) Filmmaker: Guillaume Hennenfent Find this video and other talks given by worldwide mathematicians on CIRM's Audiovisual Mathematics Library: http://library.cirm-math.fr. And discover all its functionalities: Chapter markers and keywords to watch the parts of your choice in the video Videos enriched with abstracts, bibliographies, Mathematics Subject Classification Multi-criteria search by author, title, tags, mathematical area