Logic Programs with Intensional Functions

Because programs with intensional functions are similar both to nonmonotonic causal theories and to traditional logic programs, they provide a new perspective on the relationship between these two knowledge representation languages. This is one of the reasons why they may be of interest. Another reason is that they allow us to describe effects of actions on non-Boolean fluents directly, in pretty much the same way as causal theories in the sense of (Lifschitz 1997). In traditional logic programming, non-Boolean fluents have to be encoded by Boolean fluents; to express, for instance, that the location of an object x changed between times t and t + 1 we have to write The stable model semantics treats a logic program as a mechanism for specifying its intensional predicates. In this paper we discuss a modification of that semantics in which functions, rather than predicates, are intensional. The idea of the new definition comes from nonmonotonic causal logic.

Authors

• Vladimir Lifschitz

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