Article contents
Return-time
$L^q$-spectrum for equilibrium states with potentials of summable variation
Published online by Cambridge University Press: 06 June 2022
Abstract
Let
$(X_k)_{k\geq 0}$
be a stationary and ergodic process with joint distribution
$\mu $
, where the random variables
$X_k$
take values in a finite set
$\mathcal {A}$
. Let
$R_n$
be the first time this process repeats its first n symbols of output. It is well known that
$({1}/{n})\log R_n$
converges almost surely to the entropy of the process. Refined properties of
$R_n$
(large deviations, multifractality, etc) are encoded in the return-time
$L^q$
-spectrum defined as
provided the limit exists. We consider the case where
$(X_k)_{k\geq 0}$
is distributed according to the equilibrium state of a potential
with summable variation, and we prove that
where
$P((1-q)\varphi )$
is the topological pressure of
$(1-q)\varphi $
, the supremum is taken over all shift-invariant measures, and
$q_\varphi ^*$
is the unique solution of
$P((1-q)\varphi ) =\sup _\eta \int \varphi \,d\eta $
. Unexpectedly, this spectrum does not coincide with the
$L^q$
-spectrum of
$\mu _\varphi $
, which is
$P((1-q)\varphi )$
, and it does not coincide with the waiting-time
$L^q$
-spectrum in general. In fact, the return-time
$L^q$
-spectrum coincides with the waiting-time
$L^q$
-spectrum if and only if the equilibrium state of
$\varphi $
is the measure of maximal entropy. As a by-product, we also improve the large deviation asymptotics of
$({1}/{n})\log R_n$
.
- Type
- Original Article
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- Copyright
- © The Author(s), 2022. Published by Cambridge University Press
References
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