A System of Programs for Computer-Aided Induction: A Summary

ViewGen, an algorithm and program for be­ lief ascription, represents the beliefs of agents as explicit, partitioned proposition-sets known as environments. A way of extending View-Gen to the interpretation of metaphor, and in particular to the comprehension of metaphor within the belief spaces of particular agents, has been described elsewhere. The paper re­ ports the further refinement and recent imple­ mentation of this approach, as well as sum­ marizing the argument for the claim that or­ dinary non-metaphorical belief ascription and the transfer of information in metaphors can both be seen as different manifestations of a sin­ gle environment-amalgamation process, one in which explicitly metaphorical amalgamations are triggered by "preference breaking" in the sentence being processed. This requires a con­ sideration of the scoping of metaphor with re­ spect to belief contexts, analogous to the scop­ ing of quantification and definite descriptions with respect to such contexts. As a topic of ongoing and future work, the issue of mixed metaphor, of two distinct types, is briefly ad­ dressed. press] and is embodied in a prolog program called View-Gen. The basic algorithm of this model uses the notion of default reasoning to ascribe beliefs to other agents un­ less there is evidence to prevent the ascription. Perrault [1987, 1990] and Cohen and Levesque [1985] have also recently explored a belief and speech act logic based on a single explicit default axiom. As our previous work has shown for some years, the default ascription is basically correct, but the phenomena are more complex than are normally captured by an axiomatic approach. ViewGen also avoids certain counter-intuitive assump­ tions, such as the non-persistence of ignorance about any given proposition p [Perrault, 1990]. Also such systems avoid any individual-dependent criteria for ascription, such as the individual expertise notions in Viewgen (see below). ViewGen's belief space is divided into a number of explicit, topic-specific partitions, called topic environments. ViewGen also generates a type of environment known as a viewpoint. A viewpoint consists of some person's beliefs about some topics, parcelled up into topic environments. Within ViewGen, all beliefs are ul­ timately beliefs held by the system (e.g., the system's beliefs about France, what the system believes John be­ lieves about cars, etc.) and so, trivially, lie within the system's viewpoint. The system's view of some topic (say, atoms) is picto­ rially represented as in Figure 1. This diagram contains Figure 1: The system's view of …