---
title: "Computing Least Common Subsumers in Description Logics with Existential Restrictions"
authors:
  - "Franz Baader"
  - "Ralf Küsters"
  - "Ralf Molitor"
doi: ""
url: "https://ijcai.org/proceedings/1999/15"
pdf: "https://ijcai.org/proceedings/1999/0015.pdf"
venue: "Proceedings of the Sixteenth International Joint Conference on Artificial Intelligence"
year: 1999
pages: "96-102"
track: "Automated Reasoning"
keywords:
---

# Computing Least Common Subsumers in Description Logics with Existential Restrictions

Franz Baader, Ralf Küsters, Ralf Molitor

*Proceedings of the Sixteenth International Joint Conference on Artificial Intelligence*, pages 96-102.

## Abstract

Computing the least common subsumer (lcs) is an inference task that can be used to support the "botto m-up" construction of knowledge bases for KR systems based on description logics. Previous work on how to compute the lcs has concentrated on description logics that allow for universal value restrictions , but not for existential restrictions. The main new contribution of this paper is the treatment of description logics with existential r estr ictions. Our approach for computing the lcs is based on an appropriate representation of concept descriptions by certain trees, and a characterization of subsumption by homomorphisms between these trees. Th e lcs operation then corresponds to the product operation on trees.