A Preliminary Reification of Argument Theory Change

In this article we introduce the basics for understanding the mechanisms of Argument Theory Change. In particular we reify it using Defeasible Logic Programming. In this formalism, knowledge bases are represented through defeasible logic programs. The main change operation we define over a defeasible logic program is a special kind of revision that inserts a new argument and then modifies the resulting program seeking for the argument’s warrant. Since the notion of argument refers to a set of defeasible rules, we generalize this technique in order to handle extended arguments, i.e., arguments containing also strict rules. Hence, revision using extended arguments allows us to consider program-independent arguments, which brings about new issues. A single notion of minimal change is analyzed, which refers to keep the contents of the program as much as possible. Finally, a brief discussion about the relation between our approach and the basic theory of belief revision is exposed, along with a description of other possible (more complex) minimal change principles.