Reasoning in Open Domains
Michael Gelfond, Halina Przymusinska · Logic Programming and Non-Monotonic Reasoning · 1993
In this paper we modify the semantics of epistemic specifications (and hence the answer set semantics of extended logic program and disjunctive databases) to allow for reasoning in the absence of domain--closure assumption. This modification increases the expressive power of the language and allows one to explicitly state the domain--closure and other assumptions about the domain of discourse in the language of epistemic specifications. The power of the language is demonstrated by way of examples. In particular we show how open domain assumption can be used to formalize default reasoning in the presence of anonymous exceptions to defaults. 1 Introduction Epistemic specifications were introduced in [4] as a tool for knowledge representation. They can be viewed as a generalization of "extended disjunctive databases" from [6] capable of expressing powerful forms of introspection. The semantics of an epistemic specification 5 has been given via the notion of a world view of 5 - a collect...