---
title: "A Skeptic's Menagerie: Conflictors, Preemptors, Reinstaters, and Zombies in Nonrnonotonic Inheritance"
authors:
  - "David S. Touretzky"
  - "Richmond H. Thomason"
  - "John F. Horty"
doi: ""
url: "https://ijcai.org/proceedings/1991/72"
pdf: "https://ijcai.org/proceedings/1991/0072.pdf"
venue: "Proceedings of the Twelfth International Joint Conference on Artificial Intelligence"
year: 1991
pages: "478-484"
track: "Knowledge Representation"
keywords:
---

# A Skeptic's Menagerie: Conflictors, Preemptors, Reinstaters, and Zombies in Nonrnonotonic Inheritance

David S. Touretzky, Richmond H. Thomason, John F. Horty

*Proceedings of the Twelfth International Joint Conference on Artificial Intelligence*, pages 478-484.

## Abstract

Subtle differences in the method of constructing arguments in inheritance systems can result in profound differences in both the conclusions reached and the efficiency of inference. This paper focuses on issues surrounding the defeat of arguments in nonmonotonic inheritance. Looking primarily at skeptical reasoners, we analyze several types of defeat that may be encountered, especially the defeat of defeaters. Finally, we raise some questions specific to networks that mix strict and defeasible links.