---
title: "Circumscribing Equality"
authors:
  - "Peter K. Rathmann"
  - "Marianne Winslett"
doi: ""
url: "https://ijcai.org/proceedings/1989/76"
pdf: "https://ijcai.org/proceedings/1989/0076.pdf"
venue: "Proceedings of the Eleventh International Joint Conference on Artificial Intelligence"
year: 1989
pages: "468-475"
track: "Automated Deduction"
keywords:
---

# Circumscribing Equality

Peter K. Rathmann, Marianne Winslett

*Proceedings of the Eleventh International Joint Conference on Artificial Intelligence*, pages 468-475.

## Abstract

One important facet of common-sense reasoning is the ability to draw default conclusions about the state of the world . Such an ability enables one to assume, for example, that a given bird flies in the absence of information to the contrary. One drawback of the circumscriptive approach to common-sense reasoning has been its inability to produce default conclusions about equality. For example, generally one cannot tentatively conclude that Preside nt(USA) :f- Fido using circumscription . In this paper we give a second-order axiom and model theory for circumscribing equality, and prove that they are equivalent .