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July 9, 2018, 9:30 am, Abdelraouf HECHAM (GRAPHIK)

PhD defence, on Monday, July 9th 2018, at 09:30, Building 5 – room 03.124.

La présentation sera en anglais

Composition du Jury :
Guillermo Ricardo SIMARI, Professeur, Universidad Nacional del Sur, Buenos Aires, Argentine. (Rapporteur)
Nicolas MAUDET, Professeur, Université Pierre et Marie Curie, Paris, France. (Rapporteur)
Francesca TONI, Professeure, Imperial College London, London, Royaume-Uni. (Examinatrice)
Odile PAPINI, Professeure, Université Aix-Marseille, Marseille, France. (Examinatrice)
Madalina CROITORU, MC HDR, Université de Montpellier, Montpellier, France. (Directrice de thèse)
Pierre BISQUERT, CR2, INRA, Montpellier, France. (Co-encadrant de thèse)

: “Defeasible Reasoning for Existential Rules”

Knowledge representation and reasoning on the Semantic Web has recently focused, due to practical rationale, on the subset of first order logic called existential rules.
Reasoning amounts to answering queries over a data layer of factual knowledge and an ontological layer of deductive rules and negative constraints. These negative constraints express contradictions that may arise either from the data layer (erroneous facts that lead to inconsistency) or from the ontological layer (defeasible rules that lead to incoherence). Classical query answering in presence of contradictions is trivial since from falsehood everything follows (ex falso quodlibet).
In this thesis we investigate reasoning with existential rules in presence of conflicting information and introduce defeasible existential rules reasoning. We provide three main salient results as follows. First we show that classical defeasible reasoning techniques need to be revisited for existential rules and study their theoretical and implementation related challenges. Second, we provide a new combinatorial structure that allows for diverse variants of defeasible reasoning to be captured together and study its expressivity and versatility. Third we evaluate our work with respect to the state of the art in inconsistency handling in existential rules and investigate the human appeal of such reasoning techniques.

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