The paper addresses the problem of explaining Boolean Conjunctive Query (BCQ) entailment in the presence of inconsistency within the Ontology-Based Data Access (OBDA) setting, where inconsistency is handled by the intersection of closed repairs semantics (ICR) and the ontology is represented by Datalog+/-rules. We address this problem in the case of both BCQ acceptance and failure by adopting a logical instantiation of abstract argumentation model; that is, in order to explain why the query is accepted or failed, we look for proponent or opponent sets of arguments in favor or against the query acceptance. We have also studied the computational complexity of the problem of finding an arbitrary explanation as well as all explanations.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

International audienceIn this paper we are interested in the use of argumentation for handling inconsistency in inconsistent knowledge bases expressed with existential rules. We propose an instantiation of an argumentation framework and demonstrate it is coherent, relatively grounded and non-trivial, therefore satisfying the rationality postulates from the literature. We demonstrate how argumentation semantics relate to the state of the art of handling inconsistency in this setting, allowing us to propose the first dialectical proof in the literature for a given semantics

International audienceIn the EcoBioCap project (www.ecobiocap.eu) about the next generation of packaging, a decision support system has been built that uses argumentation to deal with stakeholder preferences. However, when testing the tool the domain experts did not always understand the output of the system. The approach developed in this paper is the first step to the construction of a decision support system endowed with an explanation module. We place ourselves in the equivalent setting of inconsistent Ontology-Based Data Access (OBDA) and addresses the problem of explaining Boolean Conjunctive Query (BCQ) failure. Our proposal relies on an interactive and argumentative approach where the processes of explanation takes the form of a dialogue between the User and the Reasoner. We exploit the equivalence between argumentation and inconsistency tolerant semantics to prove that the Reasoner can always provide an answer for user’s questions