First Steps Towards Forgetting in ASPIC+

Abstract

Forgetting is a method used in several formalisms of knowledge representation and reasoning, which removes some elements from a framework while preserving the rest of the framework as much as possible. This paper investigates the process of forgetting in ASPIC+, a structured argumentation framework. We explore possible effects of forgetting operators on several levels, namely: effects on (1) the underlying language, (2) arguments and their conclusions, and (3) the justification statuses of arguments’ conclusions. We define the desired behaviour for forgetting formulas in a variant of ASPIC+, drawing from both practical considerations and existing research on forgetting in other frameworks. Furthermore, for a specific modification of the standard ASPIC+ framework, we managed to define two concrete forgetting operators, and evaluate them against the set of desiderata.