Syntax based approaches to belief revision
Bernhard Nebel · Cambridge University Press eBooks · 1992
INTRODUCTION Belief revision is the process of incorporating new information into a knowledge base while preserving consistency. Recently, belief revision has received a lot of attention in AI, which led to a number of different proposals for different applications (Ginsberg 1986; Ginsberg, Smith 1987; Dalal 1988; Gärdenfors, Makinson 1988; Winslett 1988; Myers, Smith 1988; Rao, Foo 1989; Nebel 1989; Winslett 1989; Katsuno, Mendelzon 1989; Katsuno, Mendelzon 1991; Doyle 1990). Most of this research has been considerably influenced by approaches in philosophical logic, in particular by Gärdenfors and his colleagues (Alchourrón, Gärdenfors, Makinson 1985; Gärdenfors 1988), who developed the logic of theory change , also called theory of epistemic change . This theory formalizes epistemic states as deductively closed theories and defines different change operations on such epistemic states. Syntax-based approaches to belief revision to be introduced in Section 3 have been very popular because of their conceptual simplicity. However, there also has been criticisms since the outcome of a revision operation relies an arbitrary syntactic distinctions (see, e.g., (Dalal 1988; Winslett 1988; Katsuno, Mendelzon 1989))—and for this reason such operations cannot be analyzed on the knowledge level . In (Nebel 1989) we showed that syntax-based approaches can be interpreted as assigning higher relevance to explicitly represented sentences. Based on that view, one particular kind of syntax-based revision, called base revision , was shown to fit into the theory of epistemic change. In Section 4 we generalize this result to prioritized bases .