---
title: "Keys, Nominals, and Concrete Domains"
authors:
  - "Carsten Lutz"
  - "Carlos Areces"
  - "Ian Horrocks"
  - "Ulrike Sattler"
doi: ""
url: "https://ijcai.org/proceedings/2003/52"
pdf: "https://ijcai.org/proceedings/2003/0052.pdf"
venue: "Proceedings of the Eighteenth International Joint Conference on Artificial Intelligence"
year: 2003
pages: "349-353"
track: ""
keywords:
---

# Keys, Nominals, and Concrete Domains

Carsten Lutz, Carlos Areces, Ian Horrocks, Ulrike Sattler

*Proceedings of the Eighteenth International Joint Conference on Artificial Intelligence*, pages 349-353.

## Abstract

Many description logics (DLs) combine knowledge representation on an abstract, logical level with an interface to "concrete" domains such as numbers and strings. We propose to extend such DLs with key constraints that allow the expression of statements like "US citizens are uniquely identified by their social security number". Based on this idea, we introduce a number of natural description logics and present (un)decidability results and tight NExPTrME complexity bounds.