Thirty years of Epistemic Specifications

摘要

The language of epistemic specifications and epistemic logic programs extends disjunctive logicprograms under the stable model semantics with modal constructs called subjective literals.Using subjective literals, it is possible to check whether a regular literal is true in every orsome stable models of the program, those models, in this context also called belief sets, beingcollected in a set called world view. This allows for representing, within the language, whethersome proposition should be understood accordingly to the open or the closed world assumption.Several attempts for capturing the intuitions underlying the language by means of a formalsemantics were given, resulting in a multitude of proposals that makes it difficult to understandthe current state of the art. In this article, we provide an overview of the inception of thefield and the knowledge representation and reasoning tasks it is suitable for. We also provide adetailed analysis of properties of proposed semantics, and an outlook of challenges to be tackledby future research in the area.