Invariant densities for random β -expansions

Karma Dajani; Martijn de Vries

Journal of the European Mathematical Society (2007)

  • Volume: 009, Issue: 1, page 157-176
  • ISSN: 1435-9855

Abstract

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Let β > 1 be a non-integer. We consider expansions of the form i = 1 d i / β i , where the digits ( d i ) i 1 are generated by means of a Borel map K β defined on { 0 , 1 } × [ 0 , β ( β 1 ) ] . We show existence and uniqueness of a K β -invariant probability measure, absolutely continuous with respect to m p λ , where m p is the Bernoulli measure on { 0 , 1 } with parameter p ( 0 < p < 1 ) and λ is the normalized Lebesgue measure on [ 0 , β ( β 1 ) ] . Furthermore, this measure is of the form m p μ β , p , where μ β , p is equivalent to λ . We prove that the measure of maximal entropy and m p λ are mutually singular. In case the number 1 has a finite greedy expansion with positive coefficients, the measure m p μ β , p is Markov. In the last section we answer a question concerning the number of universal expansions, a notion introduced in [EK].

How to cite

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Dajani, Karma, and de Vries, Martijn. "Invariant densities for random $\beta $-expansions." Journal of the European Mathematical Society 009.1 (2007): 157-176. <http://eudml.org/doc/277444>.

@article{Dajani2007,
abstract = {Let $\beta >1$ be a non-integer. We consider expansions of the form $\sum _\{i=1\}^\infty d_i/\beta ^i$, where the digits $(d_i)_\{i\ge 1\}$ are generated by means of a Borel map $K_\beta $ defined on $\lbrace 0,1\rbrace ^\{\mathbb \{N\}\}\times [0,\lfloor \beta \rfloor (\beta −1)]$. We show existence and uniqueness of a $K_\beta $-invariant probability measure, absolutely continuous with respect to $m_p\otimes \lambda $, where $m_p$ is the Bernoulli measure on $\lbrace 0,1\rbrace ^\{\mathbb \{N\}\}$ with parameter $p$ ($0<p<1$) and $\lambda $ is the normalized Lebesgue measure on $[0,\lfloor \beta \rfloor (\beta −1)]$. Furthermore, this measure is of the form $m_p\otimes \mu _\{\beta ,p\}$, where $\mu _\{\beta ,p\}$ is equivalent to $\lambda $. We prove that the measure of maximal entropy and $m_p\otimes \lambda $ are mutually singular. In case the number 1 has a finite greedy expansion with positive coefficients, the measure $m_p\otimes \mu _\{\beta ,p\}$ is Markov. In the last section we answer a question concerning the number of universal expansions, a notion introduced in [EK].},
author = {Dajani, Karma, de Vries, Martijn},
journal = {Journal of the European Mathematical Society},
keywords = {greedy expansions; lazy expansions; absolutely continuous invariant measures; measures of maximal entropy; Markov chains; universal expansions; greedy expansions; lazy expansions; absolutely continuous invariant measures; measures of maximal entropy; Markov chains; universal expansions},
language = {eng},
number = {1},
pages = {157-176},
publisher = {European Mathematical Society Publishing House},
title = {Invariant densities for random $\beta $-expansions},
url = {http://eudml.org/doc/277444},
volume = {009},
year = {2007},
}

TY - JOUR
AU - Dajani, Karma
AU - de Vries, Martijn
TI - Invariant densities for random $\beta $-expansions
JO - Journal of the European Mathematical Society
PY - 2007
PB - European Mathematical Society Publishing House
VL - 009
IS - 1
SP - 157
EP - 176
AB - Let $\beta >1$ be a non-integer. We consider expansions of the form $\sum _{i=1}^\infty d_i/\beta ^i$, where the digits $(d_i)_{i\ge 1}$ are generated by means of a Borel map $K_\beta $ defined on $\lbrace 0,1\rbrace ^{\mathbb {N}}\times [0,\lfloor \beta \rfloor (\beta −1)]$. We show existence and uniqueness of a $K_\beta $-invariant probability measure, absolutely continuous with respect to $m_p\otimes \lambda $, where $m_p$ is the Bernoulli measure on $\lbrace 0,1\rbrace ^{\mathbb {N}}$ with parameter $p$ ($0<p<1$) and $\lambda $ is the normalized Lebesgue measure on $[0,\lfloor \beta \rfloor (\beta −1)]$. Furthermore, this measure is of the form $m_p\otimes \mu _{\beta ,p}$, where $\mu _{\beta ,p}$ is equivalent to $\lambda $. We prove that the measure of maximal entropy and $m_p\otimes \lambda $ are mutually singular. In case the number 1 has a finite greedy expansion with positive coefficients, the measure $m_p\otimes \mu _{\beta ,p}$ is Markov. In the last section we answer a question concerning the number of universal expansions, a notion introduced in [EK].
LA - eng
KW - greedy expansions; lazy expansions; absolutely continuous invariant measures; measures of maximal entropy; Markov chains; universal expansions; greedy expansions; lazy expansions; absolutely continuous invariant measures; measures of maximal entropy; Markov chains; universal expansions
UR - http://eudml.org/doc/277444
ER -

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