Susana Nieva

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In this paper, we present an extension of the scheme HH(C) (Hereditary Harrop formulas with Constraints) with a suitable formulation of negation in order to obtain a constraint deductive database query language. In addition to constraints, our proposal includes logical con-nectives (implication and quantifiers) for defining databases and queries, which(More)
We propose a sound and complete free variable semantic tableau method for handling many-sorted preorders in a rst order logic, where functions and predicates behave monotonically or antimonotonically. We formulate additional expansion tableau rules as a more eecient alternative to adding the axioms characterizing a preordered structure. Completeness of the(More)
Combining the logic of hereditary Harrop formulas HH with a constraint system , a logic programming language is obtained that extends Horn clauses in two different directions, thus enhancing substantially the expressivity of Prolog. This new language is parametric over the constraint system. A constraint solver for a particular instance will test the(More)
Combining the logic of hereditary Harrop formulas HH with a constraint system, a logic programming language is obtained that extends Horn clauses in two different directions, thus enhancing substantially the expressivity of Prolog. The implementation of this new language requires the ability to test the satisfiability of constraints built up by means of(More)
Constraint Logic Programming (CLP) and Hereditary Harrop Formulas (HH)are two well known ways to enhance the expressivity of Horn clauses. In this paper, we present a novel combination of these two approaches. We show how to enrich the syntax and proof theory of HH with the help of a given constraint system, in such a way that the key property of HH as a(More)
Current database systems supporting recursive SQL impose restrictions on queries such as linearity, and do not implement mutual recursion. In a previous work we presented the language and prototype R-SQL to overcome those drawbacks. Now we introduce a formalization and an implementation of the database system HR-SQL that, in addition to extended recursion,(More)