Practical Argumentation Semantics for Pareto Optimality and Its Relationships with Values

摘要

This paper proposes a practical argumentation semantics specific to practical argumentation. This is motivated by our hypothesis that consequences of such argumentation should satisfy Pareto optimality because the consequences strongly depend on desires, aims, or values an individual agent or a group of agents has. We define a practical argumentation framework and two kinds of extensions, preferred and grounded extensions, with respect to each group of agents. We show that evaluating Pareto optimality can be translated to evaluating preferred extensions of a particular practical argumentation framework, and our semantics is a natural extension of Dungean semantics in terms of considering more than one defeat relation. Furthermore, we show that our semantics has the ability to identify both objectively and subjectively acceptable arguments defined on value-based argumentation frameworks. We give a generality order of four practical argumentation frameworks specified by taking into account Dungean semantics and Pareto optimality. We show that a member of preferred extensions of the most specific one is not just Pareto optimal, but also it is theoretically justified.