The role of labelled deductive systems in a formal system for defeasible argumentation

Abstract

There has been an increasing demand of a variety of logical systems, prompted by applications of logic in Al, logic prograrnming and other related areas. Labelled Deductive Systems (LDS) [Gab96] were developed as a flexible methodology to formalize such a kind of complex logical systems. In the last decade, defeasible argumentation [SL92, PV99, Ver96, BDKT97] has proven to be a confluence point for many approaches to formalizing commonsense reasoning. Different formalisms have been developed, many of them sharing cornmon fe atures. This paper outlines an argumentative LDS, in which the main issues concerning defeasible argumentation are captured within a unified logical framework. The proposed framework is defined in two stages. First, defeasible inference will be formalized by characterizing a defeasible LDS. That system wiU be then extended in order to obtain an argumentative LDS.