Determining Sets of Quasiperiods of Infinite Words

A word is quasiperiodic if it can be obtained by concatenations and overlaps of a smaller word, called a quasiperiod. Based on links between quasiperiods, right special factors and square factors, we introduce a method to determine the set of quasiperiods of a given right infinite word. Then we study the structure of the sets of quasiperiods of right infinite words and, using our method, we provide examples of right infinite words with extremal sets of quasiperiods (no quasiperiod is quasiperiodic, all quasiperiods except one are quasiperiodic, ...). Our method is also used to provide a short proof of a recent characterization of quasiperiods of the Fibonacci word. Finally we extend this result to a new characterization of standard Sturmian words using a property of their sets of quasiperiods

La parafilariose bovine : synthèse bibliographique

Ce travail rassemble l'ensemble des connaissances concernant le nématode Parafilaria bovicola et l'affection qu'il occasionne chez les bovins en Asie, en Afrique du Sud et en Europe (dont la Suède et la France). Après une présentation générale de cette parasitose, l'auteur rappelle les différentes données concernant le parasite, sa biologie et son cycle de développement, avant de décrire les aspects épidémiologiques, cliniques et lésionnels de la maladie. Sont ensuite envisagés le diagnostic, le traitement et les moyens pouvant être mis en oeuvre pour lutter contre cette helminthose. On retiendra que l'importance de la parafilariose bovine est plus liée aux pertes économiques qu'elle occasionne, du fait des saisies partielles pratiquées sur les carcasses des bovins à l'abattoir, qu'à sa gravité médicale. A l'heure actuelle, un contrôle thérapeutique efficace est possible grâce au nitroxinil et à l'ivermectine. En France, la maladie existe de façon sporadique dans differentes régions mais le diagnostic est trop peu souvent établi pour pouvoir préciser son incidence réelle

Rice-Like Theorems for Automata Networks

International audienceWe prove general complexity lower bounds on automata networks, in the style of Rice's theorem, but in the computable world. Our main result is that testing any fixed first-order property on the dynamics of an automata network is either trivial, or NP-hard, or coNP-hard. Moreover, there exist such properties that are arbitrarily high in the polynomial-time hierarchy. We also prove that testing a first-order property given as input on an automata network (also part of the input) is PSPACE-hard. Besides, we show that, under a natural effectiveness condition, any nontrivial property of the limit set of a nondeterministic network is PSPACE-hard. We also show that it is PSPACE-hard to separate deterministic networks with a very high and a very low number of limit configurations; however, the problem of deciding whether the number of limit configurations is maximal up to a polynomial quantity belongs to the polynomial-time hierarchy

System Learning of User Interactions

The case presented in this paper describes an early prototype and next steps for developing a user-adaptive recommender system using semantic analysis and matching of user profiles and content. Machine learning methods optimize semantic analysis and matching based on implicit and explicit feedback of users. The constant interaction with users provides a valuable data source that is used to improve human-computer interaction and for adapting to specific user preferences. This can lead to, among others, higher accuracy and relevance in content matching, more intuitive graphical user interfaces, improved system performance, and better prioritization of tasks

POD Analysis of Sound Generation by a Turbulent Jet

A Proper Orthogonal Decomposition (POD) is constructed for a Mach 0.9 turbulent jet using a well-validated direct numerical simulation database. Norms are defined based on near-field volume integrals of pressure, turbulence kinetic energy, streamwise velocity, and total enthalpy, two-dimensional integrals of streamswise velocity (to match experimental measurements), and far-field integrals of pressure over a sphere. We find substantially different POD modes for the different norms, and their efficiency at representing the full data is strongly dependent upon the norm and specifically which data we attempt to represent. To reproduce near-field turbulence statistics requires relatively few modes computed by a kinetic energy or pressure norm. However, a large number of the POD modes computed using a near-field norm are required to represent the sound field. The dominant near-field POD modes computed with either the near-field pressure norm or the sound field norm have the structure of wave packets