Literatura académica sobre el tema "Transformaiton de requêtes SPARQL"
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Artículos de revistas sobre el tema "Transformaiton de requêtes SPARQL"
Comparot, Catherine, Ollivier Haemmerlé y Nathalie Hernandez. "Production de requêtes SPARQL à partir de mots-clés et de patrons de requêtes". Techniques et sciences informatiques 32, n.º 7-8 (30 de octubre de 2013): 841–61. http://dx.doi.org/10.3166/tsi.32.841-861.
Texto completoLe Clerc, Jean-Yves y Romain Thomas. "Un nouveau moteur de recherche étincelant pour les archives d’Ille-et-Vilaine ?" La Gazette des archives 262, n.º 2 (2021): 67–76. http://dx.doi.org/10.3406/gazar.2021.6047.
Texto completoTesis sobre el tema "Transformaiton de requêtes SPARQL"
Lasolle, Nicolas. "Un système d'interrogation flexible pour le Web sémantique : application au corpus de la correspondance d'Henri Poincaré". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0133.
Texto completoNumerous historical works are devoted to the life and works of Henri Poincaré (1854-1912), in particular through the study and the publication of his correspondence, which consists of about 2000 letters and includes academic, private and scientific exchanges. For several years, digital projects have been carried out to store, publish and exploit corpus data by implementing standards and technologies of the Semantic Web, including RDF, RDFS and SPARQL. When browsing an RDF graph, several situations may lead to a desire of flexible querying. This term describes search methods that go beyond conventional search systems, which are restricted to exact queries and allow limited or no expression of user preferences. The main contribution of this research work is the formalization, study and applications of a flexible query mechanism based on the use of SPARQL query transformation rules. This system allows, from an initial query, an RDF graph and a set of rules, to generate SPARQL queries which can provide alternative results to those initially returned. Some rules are generic, and therefore easily transposable to other graphs, and other rules are domain-dependent. Several tools based on this mechanism have been developed to assist the digital exploitation of the Henri Poincaré correspondence. A system has been implemented to assist the manual editing of RDF data, a task which can sometimes be tedious. This system relies on domain knowledge and the use of case-based reasoning to provide an ordered list of suggestions when editing an RDF triple. The proposed flexible querying system has also been integrated into a navigation tool, which provides an interface for visual exploration of RDF graphs, and which exploits similarities between resources in a graph to generate search filters. These tools exploit knowledge associated with the correspondence corpus which is represented through various transformation rules. Through the use of this mechanism, this work also considers the evolution of research practices in history, and tends to show how such a flexible querying system can contribute to the heuristic method. The methods and tools proposed can be applied to other corpora, in particular in the context of digital humanities projects
Macina, Abdoul. "Traitement de requêtes SPARQL sur des données liées". Thesis, Université Côte d'Azur (ComUE), 2018. http://www.theses.fr/2018AZUR4230/document.
Texto completoDriven by the Semantic Web standards, an increasing number of RDF data sources are published and connected over the Web by data providers, leading to a large distributed linked data network. However, exploiting the wealth of these data sources is very challenging for data consumers considering the data distribution, their volume growth and data sources autonomy. In the Linked Data context, federation engines allow querying these distributed data sources by relying on Distributed Query Processing (DQP) techniques. Nevertheless, a naive implementation of the DQP approach may generate a tremendous number of remote requests towards data sources and numerous intermediate results, thus leading to costly network communications. Furthermore, the distributed query semantics is often overlooked. Query expressiveness, data partitioning, and data replication are other challenges to be taken into account. To address these challenges, we first proposed in this thesis a SPARQL and RDF compliant Distributed Query Processing semantics which preserves the SPARQL language expressiveness. Afterwards, we presented several strategies for a federated query engine that transparently addresses distributed data sources, while managing data partitioning, query results completeness, data replication, and query processing performance. We implemented and evaluated our approach and optimization strategies in a federated query engine to prove their effectiveness
Fokou, Pelap Géraud. "Conception d'un famework pour la relaxation des requêtes SPARQL". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2016. http://www.theses.fr/2016ESMA0014/document.
Texto completoOntology (or Knowledge base) is a formal representation of knowledge as entities and facts related to these entities. In the past years, several ontologies have been developed in academic and industrial contexts.They are generally defined with RDF language and querying with SPARQL language. A partial knowledge of instances and schema of ontology may lead user to execute queries that result in empty answers, considered as unsatisfactory. Among cooperative querying techniques which have been developed to solve the problem of empty answers, query relaxation technique is the well-known and used. It aims at weakening the conditions expressed in the original query to return alternative answers to the user. Existing work on relaxation of SPARQL queries we suffer from many drawbacks : (1) they do not allow defining in precise way the relaxation to perform with the ability to control the relaxation process (2) they do not identify the causes of failure of the request expressed by the user and (3) they do not include interactive tools to better exploit the relaxation techniques proposed. To address these limitations, this thesis proposes an advanced framework forquery relaxation SPARQL. First, this framework includes a set of relaxation operators dedicated to SPARQLqueries, to incrementally relax specific parts of the user request while controlling the relevance of the alternative responses returned w.r.t. to the user needs expressed in his request. Our framework also provides both several algorithms that identify the causes of failure of the user query and queries that are successful with a maximum number of conditions initially expressed in the failing request. This information allows the user to better understand why his request fails and execute queries that return non-empty alternative results. Finally,our framework offers intelligent relaxation strategies that rely on the causes of query failure. Such strategies reduce the execution time of the relaxation process compared to the traditional approach, which executes relaxed requests, based on their similarity to the user request, until a number of satisfactory alternative results is obtained. All contributions proposed in this framework were implemented and validated by experiments and scenarios based on the tests bench LUBM. They show the interest of our contributions w.r.t. the state of theart
El, Hassad Sara. "Learning commonalities in RDF & SPARQL". Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S011/document.
Texto completoFinding commonalities between descriptions of data or knowledge is a fundamental task in Machine Learning. The formal notion characterizing precisely such commonalities is known as least general generalization of descriptions and was introduced by G. Plotkin in the early 70's, in First Order Logic. Identifying least general generalizations has a large scope of database applications ranging from query optimization (e.g., to share commonalities between queries in view selection or multi-query optimization), to recommendation in social networks (e.g., to establish connections between users based on their commonalities between proles or searches), through exploration (e.g., to classify/categorize datasets and to identify common social graph patterns between organizations (e.g., criminal ones)). In this thesis we revisit the notion of least general generalizations in the entire Resource Description Framework (RDF) and popular conjunctive fragment of SPARQL, a.k.a. Basic Graph Pattern (BGP) queries. By contrast to the literature, we do not restrict the structure nor semantics of RDF graphs and BGPQs. Our contributions include the denition and the computation of least general generalizations in these two settings, which amounts to nding the largest set of commonalities between incomplete databases and conjunctive queries, under deductive constraints. We also provide an experimental assessment of our technical contributions
Hasan, Rakebul. "Prédire les performances des requêtes et expliquer les résultats pour assister la consommation de données liées". Thesis, Nice, 2014. http://www.theses.fr/2014NICE4082/document.
Texto completoOur goal is to assist users in understanding SPARQL query performance, query results, and derivations on Linked Data. To help users in understanding query performance, we provide query performance predictions based on the query execution history. We present a machine learning approach to predict query performances. We do not use statistics about the underlying data for our predictions. This makes our approach suitable for the Linked Data scenario where statistics about the underlying data is often missing such as when the data is controlled by external parties. To help users in understanding query results, we provide provenance-based query result explanations. We present a non-annotation-based approach to generate why-provenance for SPARQL query results. Our approach does not require any re-engineering of the query processor, the data model, or the query language. We use the existing SPARQL 1.1 constructs to generate provenance by querying the data. This makes our approach suitable for Linked Data. We also present a user study to examine the impact of query result explanations. Finally to help users in understanding derivations on Linked Data, we introduce the concept of Linked Explanations. We publish explanation metadata as Linked Data. This allows explaining derived data in Linked Data by following the links of the data used in the derivation and the links of their explanation metadata. We present an extension of the W3C PROV ontology to describe explanation metadata. We also present an approach to summarize these explanations to help users filter information in the explanation, and have an understanding of what important information was used in the derivation
Jachiet, Louis. "Sur la compilation des langages de requêtes pour le web des données : optimisation et évaluation distribuée de SPARQL". Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAM038/document.
Texto completoThe topic of my PhD is the compilation of web data query languages. More particularly, the analysisand the distributed evaluation of a such language: SPARQL. My main contributions concern theevaluation of web data queries especially for recursive queries or for distributed settings.In this thesis, I introduce μ-algebra: it is a kind of relational algebra equipped with a fixpointoperator. I present its syntax, semantics, and a translation from SPARQL with Property Paths (anew feature of SPARQL allowing some form of recursion) to this μ-algebra.I then present a type system and show how μ-algebra terms can be rewritten to terms withequivalent semantics using either classical rewrite rules of the relational world or new rules that arespecific to this μ-algebra. We demonstrate the correctness of these new rules that are introduced tohandle the rewriting of fixpoints: they allow to push filters, joins and projections inside fixpointsor to combine several fixpoints (when some condition holds).I demonstrate how these terms could be evaluated both from a general perspective and in thespecific case of a distributed evaluation. I devise a cost model for μ-algebra terms inspired by thisevaluation. With this cost model and this evaluator, several terms that are semantically equivalentcan be seen as various Query Execution Plans (QEP) for a given query. I show that the μ-algebraand its rewrite rules allow the reach of QEP that are more efficient than all QEP considered in otherexisting approaches and confirm this by an experimental comparison of several query evaluators onSPARQL queries with recursion.I investigate the use of an efficient distributed framework (Spark) to build a fast SPARQL dis-tributed query evaluator. It is based on a fragment of μ-algebra, limited to operators that havea translation into fast Spark code. The result of this has been used to implement SPARQLGX, astate of the art distributed SPARQL query evaluator.Finally, my last contribution concerns the estimation of the cardinality of solutions to a μ-algebraterm. Such estimators are key in the optimization. Indeed, most cost models for QEP rely on suchestimators and are therefore necessary to determine the most efficient QEP. I specifically considerthe conjunctive query fragment of μ-algebra (which corresponds to the well-known Basic GraphPattern fragment of SPARQL). I propose a new cardinality estimation based on statistics about thedata and implemented the method into SPARQLGX. Experiments show that this method improvesthe performance of SPARQLGX
Pradel, Camille. "D'un langage de haut niveau à des requêtes graphes permettant d'interroger le web sémantique". Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2237/.
Texto completoGraph models are suitable candidates for KR on the Web, where everything is a graph, from the graph of machines connected to the Internet, the "Giant Global Graph" as described by Tim Berners-Lee, to RDF graphs and ontologies. In that context, the ontological query answering problem is the following: given a knowledge base composed of a terminological component and an assertional component and a query, does the knowledge base implies the query, i. E. Is there an answer to the query in the knowledge base? Recently, new description logic languages have been proposed where the ontological expressivity is restricted so that query answering becomes tractable. The most prominent members are the DL-Lite and the EL families. In the same way, the OWL-DL language has been restricted and this has led to OWL2, based on the DL-Lite and EL families. We work in the framework of using graph formalisms for knowledge representation (RDF, RDF-S and OWL) and interrogation (SPARQL). Even if interrogation languages based on graphs have long been presented as a natural and intuitive way of expressing information needs, end-users do not think their queries in terms of graphs. They need simple languages that are as close as possible to natural language, or at least mainly limited to keywords. We propose to define a generic way of translating a query expressed in a high-level language into the SPARQL query language, by means of query patterns. The beginning of this work coincides with the current activity of the W3C that launches an initiative to prepare a possible new version of RDF and is in the process of standardizing SPARQL 1. 1 with entailments
Ghawi, Raji. "Ontology-based cooperation of information systems : contributions to database-to-ontology mapping and XML-to-ontology mapping". Phd thesis, Université de Bourgogne, 2010. http://tel.archives-ouvertes.fr/tel-00559089.
Texto completoAlkhateeb, Faisal. "Interroger RDF(S) avec des expressions régulières". Phd thesis, Grenoble 1, 2008. http://www.theses.fr/2008GRE10064.
Texto completoRDF is a knowledge representation language dedicated to the annotation of resources within the Semantic Web. Though RDF itself can be used as a query language for an RDF knowledge base (using RDF semantic consequence), the need for added expressivity in queries has led to define the SPARQL query language. SPARQL queries are defined on top of graph patterns that are basically RDF graphs with variables. SPARQL queries remain limited as they do not allow queries with unbounded sequences of relations (e. G. "does there exist a trip from town A to town B using only trains or buses?"). We show that it is possible to extend the RDF syntax and semantics defining the PRDF language (for Path RDF) such that SPARQL can overcome this limitation by simply replacing the basic graph patterns with PRDF graphs, effectively mixing RDF reasoning with database-inspired regular paths. We further extend PRDF to CPRDF (for Constrained Path RDF) to allow expressing constraints on the nodes of traversed paths (e. G. "Moreover, one of the correspondences must provide a wireless connection. "). We have provided sound and complete algorithms for answering queries (the query is a PRDF or a CPRDF graph, the knowledge base is an RDF graph) based upon a kind of graph homomorphism, along with a detailed complexity analysis. Finally, we use PRDF or CPRDF graphs to generalize SPARQL graph patterns, defining the PSPARQL and CPSPARQL extensions, and provide experimental tests using a complete implementation of these two query languages
Alkhateeb, Faisal. "Interroger RDF(S) avec des expressions régulières". Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00293206.
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