Varzinczak, Ivan2021-04-232021-04-2320202020http://dx.doi.org/10.1007/s13218-020-00649-8https://dl.gi.de/handle/20.500.12116/36335The present paper is a summary of a habilitation ( Habilitation à Diriger des Recherches , in French), which has been perused and evaluated by a committee composed by the following members: Franz Baader, Stéphane Demri, Hans van Ditmarsch, Sébastien Konieczny, Pierre Marquis, Marie-Laure Mugnier, Odile Papini and Leon van der Torre. It was defended on 26 November 2019 at Université d’Artois in Lens, France.Defeasible reasoningDescription logicFormal ontologiesKnowledge representation and reasoningPreferential semanticsRationalityText/Journal Article10.1007/s13218-020-00649-81610-1987