=Paper=
{{Paper
|id=Vol-1517/JOWO-15_ontolp_paper_2
|storemode=property
|title=From Classical to Consistent Query Answering under Existential Rules
|pdfUrl=https://ceur-ws.org/Vol-1517/JOWO-15_ontolp_paper_2.pdf
|volume=Vol-1517
|dblpUrl=https://dblp.org/rec/conf/ijcai/Pieris15
}}
==From Classical to Consistent Query Answering under Existential Rules==
<pdf width="1500px">https://ceur-ws.org/Vol-1517/JOWO-15_ontolp_paper_2.pdf</pdf>
<pre>
From Classical to Consistent Query Answering
           under Existential Rules
                           Andreas Pieris.
                 Institute of Information Systems,
                 Vienna University of Technology.


                                  Abstract
     We consider the well-known setting of ontology-based query answer-
 ing. In real-life applications, involving large amount of data, it is possible
 that the data are inconsistent with the ontology. Since standard ontology
 languages adhere to the classical first-order logic semantics, inconsisten-
 cies are nothing else than logical contradictions. Therefore, the classical
 inference semantics fails terribly when faced an inconsistency, since every-
 thing is inferred from a contradiction. Querying inconsistent knowledge
 bases is an intriguing new problem that gave rise to a flourishing research
 activity in the KR community. In this talk, we focus on rule-based ontol-
 ogy languages, and we demonstrate the tight connection between classical
 and consistent query answering. More precisely, we focus on the standard
 inconsistency-tolerant semantics, namely, the ABox repair (AR) seman-
 tics, and we establish generic complexity results that allow us to obtain
 in a uniform way a relatively complete picture of the complexity of our
 problem. We also discuss sound approximations of the AR semantics,
 with the aim of achieving tractability of consistent query answering in
 data complexity.




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</pre>