Ordered binary shifts with a hole

Orateur:
Wolfgang Steiner
Localisation: Université Paris Cité
Type: Séminaire COOL
Site: IHP
Salle:
salle Olga Ladyjenskaïa (ex-salle 01)
Date de début:
24/01/2025 - 10:00
Date de fin:
24/01/2025 - 11:00

In several dynamical systems on a real interval (doubling map with a  hole, Lorenz maps, unique beta-expansions, …), the orbits are coded by  binary sequences avoiding an interval. Usually, the interval of  sequences is taken with respect to the lexicographic order, and we know from Labarca and Moreira (2006) when a binary shift  with a lexicographic hole has positive entropy. Together with Komornik  and Zou (2024), I gave a “self-similar” description of this result in  terms of substitutions (or renormalisations). The aim of this talk is to extend the characterisation of positive  entropy to other piecewise monotonous orders on sequences, namely the  alternating lexicographic order, the tent map order and its inverse  (which correspond to the negative doubling map, the tent map and the V map). We obtain again a characterisation in terms of  compositions of a finite set of substitutions, but now we have a  graph-directed construction instead of arbitrary compositions of  substitutions. Moreover, renormalisation for one piecewise monotonous order can lead to another one, so that the characterisations  for the 4 orders are interconnected.