---
title: "Computing Stable Models for Nonmonotonic Existential Rules"
authors:
  - "Despoina Magka"
  - "Markus Krötzsch"
  - "Ian Horrocks"
doi: ""
url: "https://ijcai.org/proceedings/2013/157"
pdf: "https://ijcai.org/proceedings/2013/0157.pdf"
venue: "Proceedings of the Twenty-Third International Joint Conference on Artificial Intelligence"
year: 2013
pages: "1031-1037"
track: ""
keywords:
---

# Computing Stable Models for Nonmonotonic Existential Rules

Despoina Magka, Markus Krötzsch, Ian Horrocks

*Proceedings of the Twenty-Third International Joint Conference on Artificial Intelligence*, pages 1031-1037.

## Abstract

In this work, we consider function-free existential rules extended with nonmonotonic negation under a stable model semantics. We present new acyclicity and stratification conditions that identify a large class of rule sets having finite, unique stable models, and we show how the addition of constraints on the input facts can further extend this class. Checking these conditions is computationally feasible, and we provide tight complexity bounds. Finally, we demonstrate how these new methods allowed us to solve relevant reasoning problems over a real-world knowledge base from biochemistry using an off-the-shelf answer set programming engine.