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This paper is centered on the family of Dung's finite argumentation frameworks when the attacks relation is symmetric (and nonempty and irreflex-ive). We show that while this family does not contain any well-founded framework , every element of it is both coherent and relatively grounded. Then we focus on the acceptability problems for the various semantics(More)
In this paper, the problem of deriving sensible information from a collection of argumentation systems coming from different agents is addressed. The underlying argumentation theory is Dung's one: each argumentation system gives both a set of arguments and the way they interact (i.e., attack or non-attack) according to the corresponding agent. The(More)
Several propositional fragments have been considered so far as target languages for knowledge compilation and used for improving computational tasks from major AI areas (like inference, diagnosis and planning); among them are the ordered binary decision diagrams , prime implicates, prime implicants, " formulae " in decomposable negation normal form. On the(More)
Several logical languages have been considered in AI for encoding compactly preference relations over a set of alternatives. In this paper, we analyze both the expressiveness and the spatial efficiency (succinctness) of such preference representation languages. The first issue is concerned with the nature of the preorders that can be encoded (for instance,(More)
In this paper, we investigate the revision of argumenta-tion systemsà la Dung. We focus on revision as minimal change of the arguments status. Contrarily to most of the previous works on the topic, the addition of new arguments is not allowed in the revision process, so that the revised system has to be obtained by modifying the attack relation only. We(More)
The practical use of Quantified Boolean Formulae (QBFs) often calls for more than solving the validity problem QBF. For this reason we investigate the corresponding function problems whose expected outputs are policies. QBFs which do not evaluate to true do not have any solution policy, but can be of interest nevertheless ; for handling them, we introduce a(More)
We present new prudent semantics within Dung's theory of argumentation. Under such prudent semantics, two arguments cannot belong to the same extension whenever one of them attacks indirectly the other one. We argue that our semantics lead to a better handling of controversial arguments than Dung's ones. We compare the prudent inference relations induced by(More)
Recently, (Dunne et al. 2009; 2011) have suggested to weight attacks within Dung's abstract argumen-tation frameworks, and introduced the concept of WAF (Weighted Argumentation Framework). However, they use WAFs in a very specific way for relaxing attacks. The aim of this paper is to explore ways to take advantage of attacks weights within an argumentation(More)