---
title: "Completeness of the Negation as Failure Rule"
authors:
  - "Joxan Jaffar"
  - "Jean-Louis Lassez"
  - "John W. Lloyd"
doi: ""
url: "https://ijcai.org/proceedings/1983/121"
pdf: "https://ijcai.org/proceedings/1983/0121.pdf"
venue: "Proceedings of the Eighth International Joint Conference on Artificial Intelligence"
year: 1983
pages: "500-505"
track: "Logic Programming"
keywords:
---

# Completeness of the Negation as Failure Rule

Joxan Jaffar, Jean-Louis Lassez, John W. Lloyd

*Proceedings of the Eighth International Joint Conference on Artificial Intelligence*, pages 500-505.

## Abstract

Let P be a Horn clause logic program and com p(P) be its completion in th e sense of Clark . Clark gave a justification for the negation as failure rule by sho '.;in g that if a grou nd a tom A. is in the finite failur e set of P, then - A. is a logic9.l consequence of co mp ( P) , th9. t is , the neg9.tion as failure rule is so und. We prove he re that the converse also holds, that is, the negation as failure rule is compl ete .