Vincent Risch

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In this paper, we present a new method for computing extensions and for deriving formulae from a default theory. It is based on the semantic tableaux method and works for default theories with a finite set of defaults that are formulated over a decidable subset of first-order logic. We prove that all extensions (if any) of a default theory can be produced(More)
We generalize in this paper the Dung’s abstract argumentation theory in order to represent, in addition to the attack relation, a particular kind of support relation which captures knowledge of the form : “argument a is necessary to obtain argument b”. Unlike a general unspecified support, the necessity relation has the advantage to(More)
Following the approach [Schwind, Risch, 91] to Reiter’s default logic, tiffs paper attempts to define a general tableaux-based framework for tt~c cornlmtation of tile extensions for several known default k)gics. The idea is to qualify the differences b(;twecn the wlriants under considcration inside a single process that can switcil easily from one variant(More)
The correspondence between Reiter’s default reasoning and logic programming has been exhaustively studied (e.g. [1], [2], [3]). A Contrario the relation with the many variants of the initial theory of Reiter seems far less known. This paper aims to present a preliminary investigation on applying a variant of default reasoning proposed by Witold Łukaszewicz(More)
In this paper we define the notion of a compatibility relation so as to have a common framework for three nonmonotonic reasoning systems: normal logic programming, extended logic programming, and a restricted form of default logic. We show some properties of the maximal cliques of the pair-wise compatibility graph givn by the relation between the rules of(More)