Reasoning with Defeasible Arguments: Examples and Applications

This paper attempts to demonstrate the wide variety of characteristic properties of defeasible argumentation, of which nonmonotonicity is one. To do so, we introduce a simple formalism, called abstract argumentation system, with which we discuss different methods for raising arguments: forward reasoning, backward reasoning and, in particular, combinations thereof. Resource-bounded defeasible reasoning is also briefly dealt with (the prefix ‘defeasible’ is essential here). The main goal of this paper is not to tell how this should be done, but to show how these simple procedures suddenly may change in the context of defeasible argumentation. Research area 1985 Mathematics subject classification 68C01; 1987 CR classification scheme F.4.0, I.2.3, key words and phrases: nonmonotonic reasoning, defeasible argumentation, abstract argumentation system, argumentation sequence, resource-bounded defeasible reasoning.