Sufficient Conditions for First-Order and Datalog Rewritability in ELU

We study the problem of answering instance queries over non-Horn ontologies by rewriting them into Datalog programs or FirstOrder queries (FOQs). We consider the basic non-Horn language ELU , which extends EL with disjunctions. Both Datalog-rewritability and FOrewritability of instance queries have been recently shown to be decidable for ALC ontologies (and hence also for ELU); however, existing decision methods are mainly of theoretical interest. We identify two fragments of ELU for which we can compute Datalog-rewritings and FO-rewritings of instance queries, respectively, by means of a resolution-based algorithm.

[1]  Diego Calvanese,et al.  QuOnto: Querying Ontologies , 2005, AAAI.

[2]  Markus Stocker,et al.  Owlgres: A Scalable OWL Reasoner , 2008, OWLED.

[3]  Diego Calvanese,et al.  Tractable Reasoning and Efficient Query Answering in Description Logics: The DL-Lite Family , 2007, Journal of Automated Reasoning.

[4]  Diego Calvanese,et al.  High Performance Query Answering over DL-Lite Ontologies , 2012, KR.

[5]  Boris Motik,et al.  Computing Datalog Rewritings Beyond Horn Ontologies , 2013, IJCAI.

[6]  Stanislav Kikot,et al.  Modal definability of first-order formulas with free variables and query answering , 2013, J. Appl. Log..

[7]  Jeffrey F. Naughton,et al.  Data independent recursion in deductive databases , 1985, J. Comput. Syst. Sci..

[8]  Boris Motik,et al.  Reasoning in Description Logics by a Reduction to Disjunctive Datalog , 2007, Journal of Automated Reasoning.

[9]  Thomas Eiter,et al.  Query Rewriting for Horn-SHIQ Plus Rules , 2012, AAAI.

[10]  Giorgos B. Stamou,et al.  Optimized Query Rewriting for OWL 2 QL , 2011, CADE.

[11]  Boris Motik,et al.  Tractable query answering and rewriting under description logic constraints , 2010, J. Appl. Log..

[12]  Boris Motik,et al.  Data Complexity of Reasoning in Very Expressive Description Logics , 2005, IJCAI.

[13]  Alvaro del Val.  First order LUB approximations: characterization and algorithms , 2005, Artif. Intell..

[14]  Riccardo Rosati,et al.  Improving Query Answering over DL-Lite Ontologies , 2010, KR.

[15]  Haim Gaifman,et al.  Decidable Optimization Problems for Database Logic Programs (Preliminary Report) , 1988, STOC 1988.

[16]  Bart Selman,et al.  Knowledge compilation and theory approximation , 1996, JACM.

[17]  Carsten Lutz,et al.  Deciding FO-Rewritability in EL , 2012, Description Logics.

[18]  Benjamin Rossman,et al.  Homomorphism preservation theorems , 2008, JACM.

[19]  Diego Calvanese,et al.  The DL-Lite Family and Relations , 2009, J. Artif. Intell. Res..