In this paper, we study the impact of two notions of core on the output of ranking semantics in logical argumentation frameworks. We consider the existential rules fragment, a language widely used in Semantic Web and Ontology Based Data Access applications. Using burden semantics as example we show how some ranking semantics yield different outputs on the argumentation graph and its cores. We e...

In this paper, inspired in the field of belief revision, it is presented a novel operation for defining a new logic given a known logic. The operation consists in removing some (maybe undesirable) derived rule from a logic. Besides removing the ‘undesirable’ rule, this operation (called contraction) should change the logic in a minimal way. This paper presents formal definitions for contraction...

We present an approach to reasoning about statistical knowledge and degrees of belief, which is based on a combination of probabilistic reasoning from conditional constraints and default reasoning from conditional knowledge bases. More precisely, we generalize the notions of Pearl's entailment in system , Lehmann's lexicographic entailment, and Geffner's conditional entailment to strict and def...

We study here the impact of priorities on conflict resolution in inconsistent relational databases. We extend the framework of [1], which is based on the notions of repair and consistent query answer. We propose a set of postulates that an extended framework should satisfy and consider two instantiations of the framework: (locally preferred) l -repairs and (globally preferred) g -repairs. We st...

The goal of this paper is to show how modal logic may be conceived as recording the derived rules of a logical system in the system itself. This conception of modal logic was propounded by Dana Scott in the early seventies. Here, similar ideas are pursued in a context less classical than Scott's. First a family of propositional logical systems is considered, which is obtained by gradually addin...