---
title: "Constructive Tightly Grounded Autoepistemic Reasoning"
authors:
  - "Ilkka Niemelä"
doi: ""
url: "https://ijcai.org/proceedings/1991/60"
pdf: "https://ijcai.org/proceedings/1991/0060.pdf"
venue: "Proceedings of the Twelfth International Joint Conference on Artificial Intelligence"
year: 1991
pages: "399-404"
track: "Knowledge Representation"
keywords:
---

# Constructive Tightly Grounded Autoepistemic Reasoning

Ilkka Niemelä

*Proceedings of the Twelfth International Joint Conference on Artificial Intelligence*, pages 399-404.

## Abstract

The k~y concept of autoepistemic logic introduced by Moore is a stable expansion of a set of premises, i.e., a set of beliefs adopted by an agent with perfect introspection capabilities on the basis of the premises. Moore's formalization of a stable expansion, however, is nonconstructive and produces sets of beliefs which are quite weakly grounded in the premises. A new more constructive definition of the sets of beliefs of the agent is proposed. It is based on classical logic and enumerations of formulae. Considering only a certain subclass of enumerations, L-h.ierarchic enumerations, an attractive class of expansions is captured to characterize the sets of beliefs of a fully introspective agent. These L-hierarchic expansions are stable set minimal, very tightly grounded in the premises and independent of the syntactic representation of premises. Furthermore, Reiter's default logic is shown to be a special case of autoepistemic logic based on L-hierarchic expansions.