Revisiting Epistemic Specifications

TL;DR

This paper revisits the formalism of epistemic specifications, proposing new semantics, analyzing complexity, and demonstrating their effectiveness for meta-reasoning tasks, highlighting their potential for broader application.

Contribution

It introduces a new formal definition, multiple semantics, and complexity results for epistemic specifications, emphasizing their importance in knowledge representation.

Findings

New semantics for epistemic specifications proposed

Complexity analysis of the formalism conducted

Effective modeling of meta-reasoning problems demonstrated

Abstract

In 1991, Michael Gelfond introduced the language of epistemic specifications. The goal was to develop tools for modeling problems that require some form of meta-reasoning, that is, reasoning over multiple possible worlds. Despite their relevance to knowledge representation, epistemic specifications have received relatively little attention so far. In this paper, we revisit the formalism of epistemic specification. We offer a new definition of the formalism, propose several semantics (one of which, under syntactic restrictions we assume, turns out to be equivalent to the original semantics by Gelfond), derive some complexity results and, finally, show the effectiveness of the formalism for modeling problems requiring meta-reasoning considered recently by Faber and Woltran. All these results show that epistemic specifications deserve much more attention that has been afforded to them so far.