104 research outputs found
Abstract numeration systems on bounded languages and multiplication by a constant
A set of integers is -recognizable in an abstract numeration system if
the language made up of the representations of its elements is accepted by a
finite automaton. For abstract numeration systems built over bounded languages
with at least three letters, we show that multiplication by an integer
does not preserve -recognizability, meaning that there always
exists a -recognizable set such that is not
-recognizable. The main tool is a bijection between the representation of an
integer over a bounded language and its decomposition as a sum of binomial
coefficients with certain properties, the so-called combinatorial numeration
system
Numeration systems on a regular language: Arithmetic operations, Recognizability and Formal power series
Generalizations of numeration systems in which N is recognizable by a finite
automaton are obtained by describing a lexicographically ordered infinite
regular language L over a finite alphabet A. For these systems, we obtain a
characterization of recognizable sets of integers in terms of rational formal
series. We also show that, if the complexity of L is Theta (n^q) (resp. if L is
the complement of a polynomial language), then multiplication by an integer k
preserves recognizability only if k=t^{q+1} (resp. if k is not a power of the
cardinality of A) for some integer t. Finally, we obtain sufficient conditions
for the notions of recognizability and U-recognizability to be equivalent,
where U is some positional numeration system related to a sequence of integers.Comment: 34 pages; corrected typos, two sections concerning exponential case
and relation with positional systems adde
Rational series and asymptotic expansion for linear homogeneous divide-and-conquer recurrences
Among all sequences that satisfy a divide-and-conquer recurrence, the
sequences that are rational with respect to a numeration system are certainly
the most immediate and most essential. Nevertheless, until recently they have
not been studied from the asymptotic standpoint. We show how a mechanical
process permits to compute their asymptotic expansion. It is based on linear
algebra, with Jordan normal form, joint spectral radius, and dilation
equations. The method is compared with the analytic number theory approach,
based on Dirichlet series and residues, and new ways to compute the Fourier
series of the periodic functions involved in the expansion are developed. The
article comes with an extended bibliography
A Probabilistic Approach to Generalized Zeckendorf Decompositions
Generalized Zeckendorf decompositions are expansions of integers as sums of
elements of solutions to recurrence relations. The simplest cases are base-
expansions, and the standard Zeckendorf decomposition uses the Fibonacci
sequence. The expansions are finite sequences of nonnegative integer
coefficients (satisfying certain technical conditions to guarantee uniqueness
of the decomposition) and which can be viewed as analogs of sequences of
variable-length words made from some fixed alphabet. In this paper we present a
new approach and construction for uniform measures on expansions, identifying
them as the distribution of a Markov chain conditioned not to hit a set. This
gives a unified approach that allows us to easily recover results on the
expansions from analogous results for Markov chains, and in this paper we focus
on laws of large numbers, central limit theorems for sums of digits, and
statements on gaps (zeros) in expansions. We expect the approach to prove
useful in other similar contexts.Comment: Version 1.0, 25 pages. Keywords: Zeckendorf decompositions, positive
linear recurrence relations, distribution of gaps, longest gap, Markov
processe
Automatic sequences based on Parry or Bertrand numeration systems
We study the factor complexity and closure properties of automatic
sequences based on Parry or Bertrand numeration systems. These automatic
sequences can be viewed as generalizations of the more typical -automatic sequences and Pisot-automatic sequences. We show that, like -automatic
sequences, Parry-automatic sequences have sublinear factor complexity
while there exist Bertrand-automatic sequences with superlinear factor
complexity. We prove that the set of Parry-automatic sequences with
respect to a fixed Parry numeration system is not closed under taking
images by uniform substitutions or periodic deletion of letters. These
closure properties hold for -automatic sequences and
Pisot-automatic sequences, so our result shows that these properties are
lost when generalizing to Parry numeration systems and beyond.
Moreover, we show that a multidimensional sequence is -automatic with respect to a positional numeration system with regular language of numeration if and only if its -kernel is finite.</p
Numeration Systems: a Link between Number Theory and Formal Language Theory
We survey facts mostly emerging from the seminal results of Alan Cobham
obtained in the late sixties and early seventies. We do not attempt to be
exhaustive but try instead to give some personal interpretations and some
research directions. We discuss the notion of numeration systems, recognizable
sets of integers and automatic sequences. We briefly sketch some results about
transcendence related to the representation of real numbers. We conclude with
some applications to combinatorial game theory and verification of
infinite-state systems and present a list of open problems.Comment: 21 pages, 3 figures, invited talk DLT'201
Ergodic properties of {\beta}-adic Halton sequences
We investigate a parametric extension of the classical s-dimensional Halton
sequence, where the bases are special Pisot numbers. In a one- dimensional
setting the properties of such sequences have already been in- vestigated by
several authors [5, 8, 23, 28]. We use methods from ergodic theory to in order
to investigate the distribution behavior of multidimen- sional versions of such
sequences. As a consequence it is shown that the Kakutani-Fibonacci
transformation is uniquely ergodic
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