Sources of parallelism in defeasible argumentation

Abstract

In a defeasible argumentation formalism, an argument is used as a defeasible reason for supporting conclusions. A conclusion q will be considered valid only when the argument that supports it become a justification. Building a justification involves the construction of a non-defeated argument A for q. In order to establish that A is a non-defeated argument, the system look for conterarguments that could be defeaters for A. Since defeaters are arguments, there may exist defeaters for the defeaters, an so on, thus requiring a complete dialectical analysis. The language of Deafeasible Logic Programming (an extension of logic programming) provides a knowledge representation language for defeasible argumentation. In Logic programming, different kinds o parallelism have been studied, OR-parallelism, indepedent an dependent AND-parallelism, an also unification parallelism. All of these type of parallelism are at the language level. In this work we introduce different kinds of parallelism that could de exploited at different levels in a defeasible argumentation system. At the language level, all types of parallelism identified for logic programming can be used. Besides, several arguments for a conclusion q can be constructed in parallel. Once an argument A for q is found, defeaters for A could be searched in parallel. Finally, several argumentation lines in the dialectical analysis between arguments and defeaters, could be explored in parallel.