Reconnaissabilité des substitutions et complexité des suites automatiques
Recouvrement et partition en chaînes des arêtes d'un graphe cubique
Rectilinear Planar Layouts and Bipolar Orientations of Planar Graphs.
Reducing Off-Line to On-Line: an Example and Its Applications
Reducing the adjacency matrix of a tree.
Répartition des suites et substitutions
Repetition thresholds for subdivided graphs and trees
The repetition threshold introduced by Dejean and Brandenburg is the smallest real number α such that there exists an infinite word over a k-letter alphabet that avoids β-powers for all β > α. We extend this notion to colored graphs and obtain the value of the repetition thresholds of trees and “large enough” subdivisions of graphs for every alphabet size.
Repetition thresholds for subdivided graphs and trees
The repetition threshold introduced by Dejean and Brandenburg is the smallest real number α such that there exists an infinite word over a k-letter alphabet that avoids β-powers for all β > α. We extend this notion to colored graphs and obtain the value of the repetition thresholds of trees and “large enough” subdivisions of graphs for every alphabet size.
Repetitions in the Fibonacci infinite word
Représentation par automate de fonctions continues de tore
Soient et un sous-système. est une représentation en base d’une fonction du tore si pour tout point du tore, ses développements en base sont liés par le couplage aux développements en base de . On prouve que si est représentable en base alors , où . Réciproquement, toutes les fonctions de ce type sont représentables en base par un transducteur. On montre finalement que les fonctions du tore qui peuvent être représentées par automate cellulaire sont exclusivement les multiplications...
Representations of a free group of rank two by time-varying Mealy automata
In the group theory various representations of free groups are used. A representation of a free group of rank two by the so-calledtime-varying Mealy automata over the changing alphabet is given. Two different constructions of such automata are presented.
Restricted permutations from Catalan to Fine and back.
Return words in sturmian and episturmian words
Return words in Sturmian and episturmian words
Considering each occurrence of a word w in a recurrent infinite word, we define the set of return words of w to be the set of all distinct words beginning with an occurrence of w and ending exactly just before the next occurrence of w in the infinite word. We give a simpler proof of the recent result (of the second author) that an infinite word is Sturmian if and only if each of its factors has exactly two return words in it. Then, considering episturmian infinite words, which are a natural generalization...
Reversal distance for strings with duplicates: linear time approximation using hitting set.
Reverse mathematics of some topics from algorithmic graph theory
This paper analyzes the proof-theoretic strength of an infinite version of several theorems from algorithmic graph theory. In particular, theorems on reachability matrices, shortest path matrices, topological sorting, and minimal spanning trees are considered.
Rewriting on cyclic structures : equivalence between the operational and the categorical description
Rewriting on cyclic structures: Equivalence between the operational and the categorical description
We present a categorical formulation of the rewriting of possibly cyclic term graphs, based on a variation of algebraic 2-theories. We show that this presentation is equivalent to the well-accepted operational definition proposed by Barendregt et al. – but for the case of circular redexes , for which we propose (and justify formally) a different treatment. The categorical framework allows us to model in a concise way also automatic garbage collection and rules for sharing/unsharing and...
Right-cancellability of a family of operations on binary trees.
Root clustering of words
Six kinds of both of primitivity and periodicity of words, introduced by Ito and Lischke [M. Ito and G. Lischke, Math. Log. Quart. 53 (2007) 91–106; Corrigendum in Math. Log. Quart. 53 (2007) 642–643], give rise to defining six kinds of roots of a nonempty word. For 1 ≤ k ≤ 6, a k-root word is a word which has exactly k different roots, and a k-cluster is a set of k-root words u where the roots of u fulfil a given prefix relationship. We show that out of the 89 different clusters that can be considered...