Renzo Angles

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This paper studies the expressive power of SPARQL. The main result is that SPARQL and non-recursive safe Datalog with negation have equivalent expressive power, and hence, by classical results, SPARQL is equivalent from an expressive point of view to Relational Algebra. We present explicit generic rules of the transformations in both directions. Among other(More)
Graph database models can be defined as those in which data structures for the schema and instances are modeled as graphs or generalizations of them, and data manipulation is expressed by graph-oriented operations and type constructors. These models took off in the eighties and early nineties alongside object-oriented models. Their influence gradually died(More)
  • Renzo Angles
  • 2012 IEEE 28th International Conference on Data…
  • 2012
The limitations of traditional databases, in particular the relational model, to cover the requirements of current applications has lead the development of new database technologies. Among them, the Graph Databases are calling the attention of the database community because in trendy projects where a database is needed, the extraction of worthy information(More)
The Linked Data Benchmark Council (LDBC) is an EU project that aims to develop industry-strength benchmarks for graph and RDF data management systems. It includes the creation of a non-profit LDBC organization, where industry players and academia come together for managing the development of benchmarks as well as auditing and publishing official results. We(More)
RENZO ANGLES, Universidad de Talca & Center for Semantic Web Research MARCELO ARENAS, Pontificia Universidad Católica de Chile & Center for Semantic Web Research PABLO BARCELÓ, DCC, Universidad de Chile & Center for Semantic Web Research AIDAN HOGAN, DCC, Universidad de Chile & Center for Semantic Web Research JUAN REUTTER, Pontificia Universidad Católica(More)
The Subqueries functionality is a powerful feature which allows to enforce reuse, composition, rewriting and optimization in a query language. In this paper we perform a comprehensive study of the incorporation of subqueries into SPARQL. We consider several possible choices as suggested by the experience of similar languages, as well as features that(More)
Graphs have become an indispensable tool for the analysis of linked data. As with any data representation, the need for using database management systems appears when they grow in size and complexity. Associated to those needs, benchmarks appear to assess the performance of such systems in specific scenarios, representative of real use cases. In this paper(More)
The combination of the flexibility of RDF and the expressiveness of SPARQL provides a powerful mechanism to model, integrate and query data. However, these properties also mean that it is nontrivial to write performant SPARQL queries. Indeed, it is quite easy to create queries that tax even the most optimised triple stores. Currently, application developers(More)
The paper determines the algebraic and logic structure of the multiset semantics of the core patterns of SPARQL. We prove that the fragment formed by AND, UNION, OPTIONAL, FILTER, MINUS and SELECT corresponds precisely to both, the intuitive multiset relational algebra (projection, selection, natural join, arithmetic union and except), and the multiset(More)