Printed in the United Kingdom A review of current defeasible reasoning implementations 1

This article surveys existing practical implementations of both defeasible and argumentationbased reasoning engines and associated literature. We aim to summarise the current state of the art in the research area, show that there are many similiarities and connections between the various implementations and also highlight the differences regarding evaluation goals and strategies. An important goal of this paper is to argue for the need for well designed empirical evaluations, as well as formal complexity analysis, in order to justify the practical applicability of a reasoning engine. This work was partially supported by an EPSRC PhD Studentship. 2 d. bryant and p. j. krause