---
title: "Extending AGM Contraction to Arbitrary Logics"
authors:
  - "Zhi Qiang Zhuang"
  - "Zhe Wang"
  - "Kewen Wang"
  - "James P. Delgrande"
doi: ""
url: "https://ijcai.org/proceedings/2015/465"
pdf: "https://ijcai.org/proceedings/2015/0465.pdf"
venue: "Proceedings of the Twenty-Fourth International Joint Conference on Artificial Intelligence"
year: 2015
pages: "3299-3306"
track: "Special Track on Knowledge Representation and Reasoning"
keywords:
---

# Extending AGM Contraction to Arbitrary Logics

Zhi Qiang Zhuang, Zhe Wang, Kewen Wang, James P. Delgrande

*Proceedings of the Twenty-Fourth International Joint Conference on Artificial Intelligence*, pages 3299-3306.

## Abstract

Classic entrenchment-based contraction is not applicable to many useful logics, such as description logics. This is because the semantic construction refers to arbitrary disjunctions of formulas, while many logics do not fully support disjunction. In this paper, we present a new entrenchment-based contraction which does not rely on any logical connectives except conjunction. This contraction is applicable to all fragments of first-order logic that support conjunction. We provide a representation theorem for the contraction which shows that it satisfies all the AGM postulates except for the controversial Recovery Postulate, and is a natural generalisation of entrenchment-based contraction.