Sáenz Pérez, Fernando

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Sáenz Pérez

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Saenz-Perez, Fernando
Sáenz-Pérez, Fernando

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DISIA, Madrid, Spain Complutense University of Madrid (UCM)
Universidad Complutense de Madrid (UCM), Spain
FADoSS. DISIA. Universidad Complutense de Madrid, Spain
Universidad Complutense de Madrid, Spain
Universidad Complutense de Madrid
Facultad de Informática Universidad Complutense de Madrid, Spain
Facultad de Informática Universidad Complutense de Madrid

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Mostrando 1 - 7 de 7
  • Artículo
    HR-SQL: An SQL Database System with Extended Recursion and Hypothetical Reasoning
    Nieva, Susana; Sáenz Pérez, Fernando; Sánchez-Hernández, Jaime. Actas de las XV Jornadas de Programación y Lenguajes (PROLE 2015), 2015-09-15.
    In a former work we described the system and language R-SQL that overcomes some limitations of recursion of the relational database language SQL. Such limitations are non-linearity, mutual recursion, and some combinations of negation with recursion. In addition, R-SQL improved termination properties of recursive definitions. Next, this language was extended to include a restricted form of hypothetical relations and queries using assumptions, obtaining the language HR-SQL, and a preliminary implementation was developed for it. Here, we develop a new system HR-SQL from scratch and enhance the former system in several areas. First, hypothetical reasoning is fully integrated with recursive definitions. Second, the Python script generated by the system for computing the extension (materialization) of a database is now targeted to several state-of-the-art relational database systems. Third, the system has been interfaced to the integrated development environment ACIDE, allowing both a more friendly user interaction and a graphical view of the dependency graph that shows dependencies between relations. Fourth, being developed in Prolog, we have targeted it to both SICStus Prolog and SWI-Prolog, also providing standalone executables. Finally, the system has been extended with a bundle of commands, highly improving its capabilities with respect to the former system.
  • Artículo
    Experiencing Intuitionistic Logic Programming in SQL Puzzles
    Sáenz Pérez, Fernando. Actas de las XIX Jornadas de Programación y Lenguajes (PROLE 2019), 2019-09-02.
    This work presents some SQL puzzles making use of the application of intuitionistic logic programming (ILP) to implement an SQL system. ILP provides a way of declaring SQL Common Table Expressions as used to specify recursive queries and local view definitions. We present the concepts of ILP that will be used to translate SQL queries to Hypothetical Datalog, providing its syntax, an inference system and translation rules. Then, several novel SQL puzzles used during teaching standard SQL in a database subject are proposed, showing that when following the SQL standard the implemented system is more expressive than current DMBS's.
  • Artículo
    Restricted Predicates for Hypothetical Datalog
    Sáenz Pérez, Fernando. Actas de las XV Jornadas de Programación y Lenguajes (PROLE 2015), 2015-09-15.
    Hypothetical Datalog is based on an intuitionistic semantics rather than on a classical logic semantics, and embedded implications are allowed in rule bodies. While the usual implication (i.e., the neck of a Horn clause) stands for inferring facts, an embedded implication plays the role of assuming its premise for deriving its consequence. A former work introduced both a formal framework and a goal-oriented tabled implementation, allowing negation in rule bodies. While in that work positive assumptions for both facts and rules can occur in the premise, negative assumptions are not allowed. In this work, we cover this subject by introducing a new concept: a restricted predicate, which allows negative assumptions by pruning the usual semantics of a predicate. This new setting has been implemented in the deductive system DES.
  • Artículo
    Conversion of the Spanish WordNet databases into a Prolog-readable format
    Julián Iranzo, Pascual; Rigau, Germán; Sáenz Pérez, Fernando; Velasco-Crespo, Pablo. Actas de las XXI Jornadas de Programación y Lenguajes (PROLE 2022), 2022-09-05.
    WordNet is a lexical database for English that is supplied in a variety of formats, including one compatible with the Prolog programming language. Given the success and usefulness of WordNet, +AGAAYA-WordNets'' of other languages have been developed, including Spanish. The Spanish WordNet does not provide a version compatible with Prolog. This work aims to fill that gap by translating a version of the Spanish WordNet into a Prolog-compatible format. Thanks to this translation, we would obtain a set of Spanish lexical databases that would allow us to access that information using declarative techniques and the deductive capabilities of the Prolog language. Also, this work would facilitate the development of other programs to analyze the obtained information.
  • Artículo
    Formal Relational Languages in a Deductive Setting
    Sáenz Pérez, Fernando. Actas de las XVI Jornadas de Programación y Lenguajes (PROLE 2016), 2016-09-02.
    The relational data model coincides with the deductive one and, thus, formal relational query languages can be mapped to a deductive setting. These languages include, on the one hand, Tuple Relational Calculus (TRC) and Domain Relational Calculus (DRC). It can be argued that TRC can be seen as the formal basis of SQL, while DRC does the same for the semantic web language SPARQL and even the graphical relational language Query-by-Example (QBE). On the other hand, Relational Algebra (RA) is also used as a target language for intermediate compilations from SQL to executable query plans. As commonly acknowledged, RA allows a more formal setting for query optimizations than SQL. In this work, we describe the new support of TRC and DRC in the deductive system DES (which included already SQL and RA) with the aim to have an integrated system for learning database query (formal) languages based on logic.
  • Artículo
    Metapredicate Optimization for Datalog Queries through Program Analysis
    Bueno, Francisco; Correas, Jesús; Sáenz Pérez, Fernando. Actas de las XVI Jornadas de Programación y Lenguajes (PROLE 2016), 2016-09-02.
    Some systems extend Datalog in order to allow the use of constructions in which several queries are composed to produce the set of resulting tuples. These constructions include outer joins, aggregate and grouping predicates, as well as, to some extent, negation. Typically, the result of such constructions depends on the subset of the tuples in the sets initially computed. In order to optimize for efficiency these compound queries, it would be interesting to determine in advance the subsets involved in the compound construct. Static analysis can be used at compile-time to infer an over-approximation of such subsets. Very precise abstract interpretation-based static analyzers have been developed for logic languages, and in particular the use of type domains allow to infer descriptive types for the arguments of a given predicate. Using the extensional description of the types inferred, the Datalog program can then be transformed to use the inferred subsets instead of the original queries. Here, we propose a source-to-source transformation of Datalog programs based on static analysis for optimizing queries involving outer join, negation, aggregate and grouping predicates. This approach has been tested in the DES system, using CiaoPP (a language preprocessor for Prolog) for inferring descriptive types. Some preliminary experiments show promising results.
  • Artículo
    Integrating WordNet into Bousi~Prolog
    Julián Iranzo, Pascual; Sáenz Pérez, Fernando. Actas de las XIX Jornadas de Programación y Lenguajes (PROLE 2019), 2019-09-02.
    In this paper we provide techniques to integrate WordNet into a Fuzzy Logic Programming System. Because WordNet relates words but does not give graded information of the relation between them, we have implemented standard similarity measures and new directives that allow us to generate the proximity equations linking two words with an approximation degree. Proximity equations are the key syntactic structures that, in addition to a weak unification algorithm, make possible a flexible query answering process in this kind of programming languages.