Comparing Defeasible Logics

In this paper we seek to formally establish the similarities and differences between two formalizations of defeasible reasoning: the defeasible logics of Nute and Maier, and defeasible logics in the framework of Antoniou et al. Both families of logics have developed from earlier logics of Nute, but their development has followed different paths and they are formulated very differently. We examine these logics from the standpoint of relative inference strength – how much the logics can infer from a given theory – and relative expressiveness – how well one logic can simulate another. We identify similarities between logics in the two families and pinpoint aspects that distinguish them.