Abstract
We address the issue of Ontology-Based Data Access which consists of exploiting the semantics expressed in ontologies while querying data. Ontologies are represented in the framework of existential rules, also known as Datalog+/-. We focus on the backward chaining paradigm, which involves rewriting the query (assumed to be a conjunctive query, CQ) into a set of CQs (seen as a union of CQs). The proposed algorithm accepts any set of existential rules as input and stops for so-called finite unification sets of rules (fus). The rewriting step relies on a graph notion, called a piece, which allows to identify subsets of atoms from the query that must be processed together. We first show that our rewriting method computes a minimal set of CQs when this set is finite, i.e., the set of rules is a fus. We then focus on optimizing the rewriting step. First experiments are reported.
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König, M., Leclère, M., Mugnier, ML., Thomazo, M. (2012). A Sound and Complete Backward Chaining Algorithm for Existential Rules. In: Krötzsch, M., Straccia, U. (eds) Web Reasoning and Rule Systems. RR 2012. Lecture Notes in Computer Science, vol 7497. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-33203-6_10
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DOI: https://doi.org/10.1007/978-3-642-33203-6_10
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