---
title: "Skeptical Inheritance: Computing the Intersection of Credulous Extensions"
authors:
  - "Lynn Andrea Stein"
doi: ""
url: "https://ijcai.org/proceedings/1989/185"
pdf: "https://ijcai.org/proceedings/1989/0185.pdf"
venue: "Proceedings of the Eleventh International Joint Conference on Artificial Intelligence"
year: 1989
pages: "1153-1159"
track: "Commonsense Reasoning"
keywords:
---

# Skeptical Inheritance: Computing the Intersection of Credulous Extensions

Lynn Andrea Stein

*Proceedings of the Eleventh International Joint Conference on Artificial Intelligence*, pages 1153-1159.

## Abstract

Ideally skeptical inheritance supports exactly those inferences true in every credulous extension of an inheritance hierarchy. We provide a formal definition of ideally skeptical inheritance. We show that two path -based approaches fail to capture ideally skeptical inheritance, and that there are inheritance hierarchies for which there are more always-true inferences than always-supported paths. We describe an ATMS-like scheme that computes ideally skeptical inheritance and represents hierarchical dependencies using a limited form of Boolean satisfiability. Finally, we demonstrate a preemption (specificity) strategy for which ideally skeptical inheritance is polynomial-time computable.