Integrating Dialectical and Accrual Modes of Argumentation

This paper argues that accrual should be modelled in terms of reasoning about the application of preferences to sets of arguments, and shows how such reasoning can be formalised within metalevel argumentation frameworks. These frameworks adopt the same machinery and level of abstraction as Dung's argumentation framework. We thus provide a dialectical argumentation semantics that integrates accrual, and illustrate our approach by instantiating our framework with the arguments and attacks defined by an object level formalism that accommodates reasoning about priorities over sets of rules.