References of "Charlier, Emilie"
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See detailState complexity of testing divisibility
Charlier, Emilie ULg; Rampersad, Narad ULg; Rigo, Michel ULg et al

in McQuillan, Ian, Pighizzini, Giovanni (Ed.) Proceedings Twelfth Annual Workshop on Descriptional Complexity of Formal Systems (2010, August)

Under some mild assumptions, we study the state complexity of the trim minimal automaton accepting the greedy representations of the multiples of m>=2 for a wide class of linear numeration systems. As an ... [more ▼]

Under some mild assumptions, we study the state complexity of the trim minimal automaton accepting the greedy representations of the multiples of m>=2 for a wide class of linear numeration systems. As an example, the number of states of the trim minimal automaton accepting the greedy representations of mN in the Fibonacci system is exactly 2m^2. [less ▲]

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See detailStructure of the minimal automaton of a numeration language
Charlier, Emilie ULg; Rampersad, Narad ULg; Rigo, Michel ULg et al

in Actes de LaCIM 2010 (2010, August)

We study the structure of automata accepting the greedy representations of N in a wide class of numeration systems. We describe the conditions under which such automata can have more than one strongly ... [more ▼]

We study the structure of automata accepting the greedy representations of N in a wide class of numeration systems. We describe the conditions under which such automata can have more than one strongly connected component and the form of any such additional components. Our characterization applies, in particular, to any automaton arising from a Bertrand numeration system. Furthermore, we show that for any automaton A arising from a system with a dominant root beta>1, there is a morphism mapping A onto the automaton arising from the Bertrand system associated with the number beta. [less ▲]

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See detailRepresenting real numbers in a generalized numeration system
Charlier, Emilie ULg

Conference (2010, June)

We show how to represent an interval of real numbers in an abstract numeration system built on a language that is not necessarily regular. As an application, we consider representations of real numbers ... [more ▼]

We show how to represent an interval of real numbers in an abstract numeration system built on a language that is not necessarily regular. As an application, we consider representations of real numbers using the Dyck language. We also show that our framework can be applied to the rational base numeration systems. [less ▲]

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See detailStructure of the minimal automaton of a numeration language and applications to state complexity
Charlier, Emilie ULg; Rampersad, Narad ULg; Rigo, Michel ULg et al

in Actes des Journées Montoises d'Informatique Théorique (2010)

We study the structure of automata accepting the greedy representations of N in a wide class of numeration systems. We describe the conditions under which such automata can have more than one strongly ... [more ▼]

We study the structure of automata accepting the greedy representations of N in a wide class of numeration systems. We describe the conditions under which such automata can have more than one strongly connected component and the form of any such additional components. Our characterization applies, in particular, to any automaton arising from a Bertrand numeration system. Furthermore, we show that for any automaton A arising from a system with a dominant root > 1, there is a morphism mapping A onto the automaton arising from the Bertrand system associated with the number . Under some mild assumptions, we also study the state complexity of the trim minimal automaton accepting the greedy representations of the multiples of m>=2 for a wide class of linear numeration systems. As an example, the number of states of the trim minimal automaton accepting the greedy representations of mN in the Fibonacci system is exactly 2m^2. [less ▲]

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See detailMultidimensional generalized automatic sequences and shape-symmetric morphic words
Charlier, Emilie ULg; Kärki, Tomi; Rigo, Michel ULg

in Discrete Mathematics (2010), 310

An infinite word is S-automatic if, for all n>=0, its (n+1)st letter is the output of a deterministic automaton fed with the representation of n in the numeration system S. In this paper, we consider an ... [more ▼]

An infinite word is S-automatic if, for all n>=0, its (n+1)st letter is the output of a deterministic automaton fed with the representation of n in the numeration system S. In this paper, we consider an analogous definition in a multidimensional setting and study its relation to the shapesymmetric infinite words introduced by Arnaud Maes. More precisely, for d>1, we show that a multidimensional infinite word x over a finite alphabet is S-automatic for some abstract numeration system S built on a regular language containing the empty word if and only if x is the image by a coding of a shape-symmetric infinite word. [less ▲]

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See detailAbstract Numeration Systems : Recognizability, Decidability, Multidimensional S-Automatic Words, and Real Numbers
Charlier, Emilie ULg

Doctoral thesis (2009)

In this dissertation we study and we solve several questions regarding abstract numeration systems. Each particular problem is the focus of a chapter. The first problem concerns the study of the ... [more ▼]

In this dissertation we study and we solve several questions regarding abstract numeration systems. Each particular problem is the focus of a chapter. The first problem concerns the study of the preservation of recognizability under multiplication by a constant in abstract numeration systems built on polynomial regular languages. The second is a decidability problem, which has been already studied notably by J. Honkala and A. Muchnik and which is studied here for two new cases: the linear positional numeration systems and the abstract numeration systems. Next, we focus on the extension to the multidimensional setting of a result of A. Maes and M. Rigo regarding S-automatic infinite words. Finally, we propose a formalism to represent real numbers in the general framework of abstract numeration systems built on languages that are not necessarily regular. We end by a list of open questions in the continuation of the present work. [less ▲]

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See detailA characterization of multidimensional S-automatic sequences
Charlier, Emilie ULg; Kärki, Tomi ULg; Rigo, Michel ULg

in Actes des rencontres du CIRM, 1 (2009)

An infinite word is S-automatic if, for all n ≥ 0, its (n + 1)st letter is the output of a deterministic automaton fed with the representation of n in the considered numeration system S. In this extended ... [more ▼]

An infinite word is S-automatic if, for all n ≥ 0, its (n + 1)st letter is the output of a deterministic automaton fed with the representation of n in the considered numeration system S. In this extended abstract, we consider an analogous definition in a multidimensional setting and present the connection to the shape-symmetric infinite words introduced by Arnaud Maes. More precisely, for d ≥ 2, we state that a multidimensional infinite word x : N^d → \Sigma over a finite alphabet \Sigma is S-automatic for some abstract numeration system S built on a regular language containing the empty word if and only if x is the image by a coding of a shape-symmetric infinite word. [less ▲]

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See detailMultidimensional generalized automatic sequences and shape-symmetric morphic words
Charlier, Emilie ULg; Kärki, Tomi; Rigo, Michel ULg

in Proceedings of AutoMathA (2009)

An infinite word is S-automatic if, for all n ≥ 0, its (n + 1)st letter is the output of a deterministic automaton fed with the representation of n in the considered numeration system S. In this paper, we ... [more ▼]

An infinite word is S-automatic if, for all n ≥ 0, its (n + 1)st letter is the output of a deterministic automaton fed with the representation of n in the considered numeration system S. In this paper, we consider an analogous definition in a multidimensional setting and study the relationship with the shape-symmetric infinite words as introduced by Arnaud Maes. Precisely, for d ≥ 2, we show that a multidimensional infinite word x : N^d → Σ over a finite alphabet Σ is S-automatic for some abstract numeration system S built on a regular language containing the empty word if and only if x is the image by a coding of a shape-symmetric infinite word. [less ▲]

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See detailA Decision Problem for Ultimately Periodic Sets in Non-standard Numeration Systems
Bell, Jason; Charlier, Emilie ULg; Fraenkel, Aviezri et al

in International Journal of Algebra & Computation (2009), 19

Consider a non-standard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0,1} without two consecutive 1. Given a set X of integers ... [more ▼]

Consider a non-standard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0,1} without two consecutive 1. Given a set X of integers such that the language of their greedy representations in this system is accepted by a finite automaton, we consider the problem of deciding whether or not X is a finite union of arithmetic progressions. We obtain a decision procedure for this problem, under some hypothesis about the considered numeration system. In a second part, we obtain an analogous decision result for a particular class of abstract numeration systems built on an infinite regular language. [less ▲]

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See detailA decision problem for ultimately periodic sets in non-standard numeration systems
Charlier, Emilie ULg

Scientific conference (2008, December)

Given a linear numeration system U and a set X (include in N) such that repU(X) is recognized by a (deterministic) finite automaton. Is it decidable whether or not X is ultimately periodic, i.e., whether ... [more ▼]

Given a linear numeration system U and a set X (include in N) such that repU(X) is recognized by a (deterministic) finite automaton. Is it decidable whether or not X is ultimately periodic, i.e., whether or not X is a finite union of arithmetic progressions? Honkala showed that this problem turns out to be decidable for the usual b-ary numeration system (b greater than 2) defined by U_n = bU_{n-1} for n greater than 1 and U_0 = 1. In this work, we give a decision procedure for this problem for a large class of linear numeration systems. [less ▲]

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See detailA decision problem for ultimately periodic sets in non-standard numeration systems
Charlier, Emilie ULg

Conference (2008, May)

We consider the following decidability problem: Given a linear numeration system U and a set X ⊆ N such that rep_U(X) is recognized by a (deterministic) finite automaton. Is it decidable whether or not X ... [more ▼]

We consider the following decidability problem: Given a linear numeration system U and a set X ⊆ N such that rep_U(X) is recognized by a (deterministic) finite automaton. Is it decidable whether or not X is ultimately periodic, i.e., whether or not X is a finite union of arithmetic progressions? In this work, we give a decision procedure for this problem whenever U is a linear numeration system such that N is U -recognizable and satisfying a relation of the form U_{i+k} = a_1 U_{i+k−1} + · · · + a_k U_i with a_k = ±1 (the main reason for this assumption is that 1 and −1 are the only two integers invertible modulo n for all n ≥ 2). [less ▲]

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See detailSystèmes de numération
Charlier, Emilie ULg

Scientific conference (2008, February)

Dans cet exposé, je propose une introduction aux systèmes de numération en général : bases entières, numérations linéaires, numérations abstraites. Je donnerai les premiers résultats et attirerai l ... [more ▼]

Dans cet exposé, je propose une introduction aux systèmes de numération en général : bases entières, numérations linéaires, numérations abstraites. Je donnerai les premiers résultats et attirerai l'attention sur différents axes de recherche possibles. [less ▲]

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See detailAbstract numeration systems on bounded languages and multiplication by a constant
Charlier, Emilie ULg; Rigo, Michel ULg; Steiner, Wolfgang

in INTEGERS: Electronic Journal of Combinatorial Number Theory (2008), 8(1-A35), 1-19

A set of integers is $S$-recognizable in an abstract numeration system $S$ if the language made up of the representations of its elements is accepted by a finite automaton. For abstract numeration systems ... [more ▼]

A set of integers is $S$-recognizable in an abstract numeration system $S$ 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 $\lambda\ge2$ does not preserve $S$-recognizability, meaning that there always exists a $S$-recognizable set $X$ such that $\lambda X$ is not $S$-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. [less ▲]

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See detailA decision problem for ultimately periodic sets in non-standard numeration systems
Charlier, Emilie ULg; Rigo, Michel ULg

in Actes des Journées Montoises d'Informatique Théorique (2008)

Consider a non-standard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0, 1} without two consecutive 1. Given a set X of ... [more ▼]

Consider a non-standard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0, 1} without two consecutive 1. Given a set X of integers such that the language of their greedy representations in this system is accepted by a finite automaton, we consider the problem of deciding whether or not X is a finite union of arithmetic progressions. We obtain a decision procedure under some hypothesis about the considered numeration system. In a second part, we obtain an analogous decision result for a particular class of abstract numeration systems built on an infinite regular language. [less ▲]

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See detailA Decision Problem for Ultimately Periodic Sets in Non-standard Numeration Systems
Charlier, Emilie ULg; Rigo, Michel ULg

in Lecture Notes in Computer Science (2008), 5162

Consider a non-standard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0, 1} without two consecutive 1. Given a set X of ... [more ▼]

Consider a non-standard numeration system like the one built over the Fibonacci sequence where nonnegative integers are represented by words over {0, 1} without two consecutive 1. Given a set X of integers such that the language of their greedy representations in this system is accepted by a finite automaton, we consider the problem of deciding whether or not X is a finite union of arithmetic progressions. We obtain a decision procedure under some hypothesis about the considered numeration system. In a second part, we obtain an analogous decision result for a particular class of abstract numeration systems built on an infinite regular language. [less ▲]

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See detailAbstract numeration systems
Charlier, Emilie ULg

Conference (2007, May)

In this talk, I will introduce abstract numeration systems in general and present some results I have regarding operation preserving regularity. In particular, I will focus on multiplication by a constant.

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See detailStructural properties of bounded languages with respect to multiplication by a constant
Charlier, Emilie ULg

Conference (2007, April)

Generalizations of positional number systems in which N is recognizable by finite automata are obtained by describing an arbitrary infinite regular language according to the genealogical ordering. More ... [more ▼]

Generalizations of positional number systems in which N is recognizable by finite automata are obtained by describing an arbitrary infinite regular language according to the genealogical ordering. More precisely, an abstract numeration system is a triple S = (L, Σ, <) where L is an infinite language over the totally ordered alphabet (Σ, <). Enumerating the elements of L genealogically with respect to < leads to a one-to-one map rS from N onto L. To any natural number n, it assigns the (n + 1)th word of L, its S-representation, while the inverse map valS sends any word belonging to L onto its numerical value. A subset X is said to be S-recognizable if rS (X) is a regular subset of L. We study the preservation of recognizability of a set of integers after multiplication by a constant for abstract numeration systems built over a bounded language. [less ▲]

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See detailAbstract numeration systems and recognizability
Charlier, Emilie ULg

Conference (2007, January)

In this talk, I will present some results concerning multiplication by a constant in an abstract numeration system built on a bounded language. More precisely, we will show that this operation does not ... [more ▼]

In this talk, I will present some results concerning multiplication by a constant in an abstract numeration system built on a bounded language. More precisely, we will show that this operation does not preserve regularity, and therefore cannot be computed by a finite automaton. [less ▲]

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See detailStrutural properties of bounded languages with respect to multiplication by a constant
Charlier, Emilie ULg

Conference (2006, October)

We consider the preservation of recognizability of a set of integers after multiplication by a constant for numeration systems built over a bounded language. As a corollary we show that any nonnegative ... [more ▼]

We consider the preservation of recognizability of a set of integers after multiplication by a constant for numeration systems built over a bounded language. As a corollary we show that any nonnegative integer can be written as a sum of binomial coefficients with some prescribed properties. [less ▲]

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See detailConservation du caractère reconnaissable par opérations arithmétiques dans un système de numération abstrait
Charlier, Emilie ULg

Master of advanced studies dissertation (2006)

In this thesis, I study the stability of recognizability under arithmetic operations like addition, multiplication by a constant or multiplication, in an abstract numeration system. The main result ... [more ▼]

In this thesis, I study the stability of recognizability under arithmetic operations like addition, multiplication by a constant or multiplication, in an abstract numeration system. The main result presented in this work concerns the abstract numeration system built on the bounded language a^*b^*. It shows that, in this case, multiplication by a constant preserves recognizability if and only if this constant is an odd square. I end this text by providing some partial results of a generalization to abstract numeration system built on any bounded language. [less ▲]

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