Revisiting LFSMs

Linear Finite State Machines (LFSMs) are particular primitives widely used in information theory, coding theory and cryptography. Among those linear automata, a particular case of study is Linear Feedback Shift Registers (LFSRs) used in many cryptographic applications such as design of stream ciphers or pseudo-random generation. LFSRs could be seen as particular LFSMs without inputs. In this paper, we first recall the description of LFSMs using traditional matrices representation. Then, we introduce a new matrices representation with polynomial fractional coefficients. This new representation leads to sparse representations and implementations. As direct applications, we focus our work on the Windmill LFSRs case, used for example in the E0 stream cipher and on other general applications that use this new representation. In a second part, a new design criterion called diffusion delay for LFSRs is introduced and well compared with existing related notions. This criterion represents the diffusion capacity of an LFSR. Thus, using the matrices representation, we present a new algorithm to randomly pick LFSRs with good properties (including the new one) and sparse descriptions dedicated to hardware and software designs. We present some examples of LFSRs generated using our algorithm to show the relevance of our approach.Comment: Submitted to IEEE-I

A Visual Language for Web Querying and Reasoning

As XML is increasingly being used to represent information on the Web, query and reasoning languages for such data are needed. This article argues that in contrast to the navigational approach taken in particular by XPath and XQuery, a positional approach as used in the language Xcerpt is better suited for a straightforward visual representation. The constructs of the pattern- and rule-based query language Xcerpt are introduced and it is shown how the visual representation visXcerpt renders these constructs to form a visual query language for XML

Completing Queries: Rewriting of IncompleteWeb Queries under Schema Constraints

Reactive Web systems, Web services, and Web-based publish/ subscribe systems communicate events as XML messages, and in many cases require composite event detection: it is not sufficient to react to single event messages, but events have to be considered in relation to other events that are received over time. Emphasizing language design and formal semantics, we describe the rule-based query language XChangeEQ for detecting composite events. XChangeEQ is designed to completely cover and integrate the four complementary querying dimensions: event data, event composition, temporal relationships, and event accumulation. Semantics are provided as model and fixpoint theories; while this is an established approach for rule languages, it has not been applied for event queries before

Identification of Design Principles

This report identifies those design principles for a (possibly new) query and transformation language for the Web supporting inference that are considered essential. Based upon these design principles an initial strawman is selected. Scenarios for querying the Semantic Web illustrate the design principles and their reflection in the initial strawman, i.e., a first draft of the query language to be designed and implemented by the REWERSE working group I4

A Generic Module System forWeb Rule Languages: Divide and Rule

An essential feature in practically usable programming languages is the ability to encapsulate functionality in reusable modules. Modules make large scale projects tractable by humans. For Web and Semantic Web programming, many rule-based languages, e.g. XSLT, CSS, Xcerpt, SWRL, SPARQL, and RIF Core, have evolved or are currently evolving. Rules are easy to comprehend and specify, even for non-technical users, e.g. business managers, hence easing the contributions to the Web. Unfortunately, those contributions are arguably doomed to exist in isolation as most rule languages are conceived without modularity, hence without an easy mechanism for integration and reuse. In this paper a generic module system applicable to many rule languages is presented. We demonstrate and apply our generic module system to a Datalog-like rule language, close in spirit to RIF Core. The language is gently introduced along the EU-Rent use case. Using the Reuseware Composition Framework, the module system for a concrete language can be achieved almost for free, if it adheres to the formal notions introduced in this paper

Effective and Efficient Data Access in the Versatile Web Query Language Xcerpt

Access to Web data has become an integral part of many applications and services. In the past, such data has usually been accessed through human-tailoredHTMLinterfaces.Nowadays, rich client interfaces in desktop applications or, increasingly, in browser-based clients ease data access and allow more complex client processing based on XML or RDF data retrieved throughWeb service interfaces. Convenient specifications of the data processing on the client and flexible, expressive service interfaces for data access become essential in this context.Web query languages such as XQuery, XSLT, SPARQL, or Xcerpt have been tailored specifically for such a setting: declarative and efficient access and processing ofWeb data. Xcerpt stands apart among these languages by its versatility, i.e., its ability to access not just oneWeb format but many. In this demonstration, two aspects of Xcerpt are illustrated in detail: The first part of the demonstration focuses on Xcerpt’s pattern matching constructs and rules to enable effective and versatile data access. It uses a concrete practical use case from bibliography management to illustrate these language features. Xcerpt’s visual companion language visXcerpt is used to provide an intuitive interface to both data and queries. The second part of the demonstration shows recent advancements in Xcerpt’s implementation focusing on experimental evaluation of recent complexity results and optimization techniques, as well as scalability over a number of usage scenarios and input sizes

Modular Web Queries — From Rules to Stores

Even with all the progress in Semantic technology, accessing Web data remains a challenging issue with new Web query languages and approaches appearing regularly. Yet most of these languages, including W3C approaches such as XQuery and SPARQL, do little to cope with the explosion of the data size and schemata diversity and richness on the Web. In this paper we propose a straightforward step toward the improvement of this situation that is simple to realize and yet effective: Advanced module systems that make partitioning of (a) the evaluation and (b) the conceptual design of complex Web queries possible. They provide the query programmer with a powerful, but easy to use high-level abstraction for packaging, encapsulating, and reusing conceptually related parts (in our case, rules) of a Web query. The proposed module system combines ease of use thanks to a simple core concept, the partitioning of rules and their consequences in flexible “stores”, with ease of deployment thanks to a reduction semantics. We focus on extending the rule-based Semantic Web query language Xcerpt with such a module system though the same approach can be applied to other (rule-based) languages as well

Trajectoire(s) de l’hydrosystème Saône-Rhône au paléoanthropocène

Notre PCR a pour objectif de documenter le paléoanthropocène rhodanien (depuis le Néolithique), de proposer des scenarii socio-environnementaux rétrospectifs, d’associer des connaissances sur les temporalités et processus du paléoanthropocène fluvial rhodanien, en insistant sur les principales bifurcations historiques de sa trajectoire (jusqu’au court-circuitage anthropogénique se son cours au xxe s.). Il aborde trois principales questions sur un continuum nord-sud de plus de 600 km, le co..

Milieux et peuplements en Bas-Dauphiné

Date de l'opération : 2007 (PC) L’étude des sources historiques et cartographiques depuis la fin du Moyen Âge La période comprise entre la fin du Moyen Âge et le XIXe s. a fait l’objet de nouvelles recherches en 2007 qui documentent l’occupation et la gestion du sol et la démographie historique des quatre ou cinq derniers siècles, une période qui a vu un développement sociétal considérable dans les milieux palustres et alluviaux des Basses Terres dauphinoises, lors d’un épisode de péjoration ..

Comment élaborer un environnement interactif adapté à la formation par le projet ? Étude d'un processus de conception

International audienceAujourd'hui, la formation ouverte et à distance (FOAD), dans l'enseignement supérieur en France, a dépassé le stade des projets et des expérimentations pilotes. On parle de campus numérique, de plate-forme de formation à distance, de LCMS, de générateur de documents hypermédias, etc. En ce sens, les ingénieries et recherches, dans le domaine, semblent s'attacher prioritairement à des questions de médiatisation de contenus, de production standardisée, d'indexation normée par des méta-données en vue de leur ré-exploitation et/ou mutualisation. Comme si les problématiques de contenus étaient premières au regard de celles des relations de formation. D'autres travaux, comme ceux sur l'apprentissage coopératif et le travail collaboratif (Bourguin et al., 2002), mettent cependant l'accent sur l'instrumentation des relations et interactions sociales et cognitives des acteurs de la formation. C'est dans une perspective proche, bien qu'un peu différente, que s'inscrivent nos travaux, qui cherchent à articuler pratiques de travail et de recherche, par la modélisation d'instruments et de dispositifs, développés à partir de situations concrètes de travail. Notre démarche a consisté, en premier lieu, à conduire un processus d'ingénierie en réponse à une commande d'instrumentation d'un dispositif de formation existant. L'analyse de cette demande, la prise en compte de son contexte et le processus de conception lui-même ont permis de travailler sur une triple problématique : pédagogique, économique, technologique. Ce processus d'ingénierie a débouché sur la construction d'un dispositif, intitulé Appui et la mise au point d'une plate-forme, visant à prendre en compte cette problématique. Les usages du dispositif et leur réinterrogation nous ont permis, en second lieu, d'envisager, de façon plus générale, une modélisation de l'accompagnement de projet à distance à partir du système de représentation des actions et interactions, intégré dans le dispositif. En conclusion de l'article, nous situerons les limites du modèle élaboré, en questionnant les conditions de sa reproductibilité