# Asymptotic behaviour of iterated function systems and applications to variable length Markov chains

Abstract : The purpose of this thesis is the study of the asymptotic behaviour of iterated function systems (IFS). In a first part, we will introduce the notions related to the study of such systems and we will remind different applications of IFS such as random walks on graphs or aperiodic tilings, random dynamical systems, proteins classification or else $q$-repeated measures. We will focus on two other applications : the chains of infinite order and the variable length Markov chains. We will give the main results in the literature concerning the study of invariant measures for IFS and those for the calculus of the Hausdorff dimension. The second part will be dedicated to the study of a class of iterated function systems (IFSs) with non-overlapping or just-touching contractions on closed real intervals and adapted piecewise constant transition probabilities. We give criteria for the existence and the uniqueness of an invariant probability measure for the IFSs and for the asymptotic stability of the system in terms of bounds of transition probabilities. Additionally, in case there exists a unique invariant measure and under some technical assumptions, we obtain its exact Hausdorff dimension as the ratio of the entropy over the Lyapunov exponent. This result extends the formula, established in the literature for continuous transition probabilities, to the case considered here of piecewise constant probabilities. The last part is dedicated to a special case of IFS : Variable Length Markov Chains (VLMC). We will show that under a weak non-nullness condition and continuity for the ultrametric distance of the transition probabilities, they admit a unique invariant measure which is attractive for the weak convergence.
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Cited literature [54 references]

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Submitted on : Wednesday, April 25, 2018 - 9:39:05 AM
Last modification on : Wednesday, September 9, 2020 - 5:13:04 AM

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DUBARRY_Blandine.pdf
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• HAL Id : tel-01777729, version 1

### Citation

Blandine Dubarry. Asymptotic behaviour of iterated function systems and applications to variable length Markov chains. Probability [math.PR]. Université Rennes 1, 2017. English. ⟨NNT : 2017REN1S114⟩. ⟨tel-01777729⟩

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