Abstract. The Description Logic EL has recently drawn considerable attention since, on the one hand, important inference problems such as the subsumption problem are polynomial. On the other hand, EL is used to define large biomedical ontologies. Unification in Description Logics has been proposed

For a developer or user of a DL-based ontology, it is often quite hard to understand why a certain consequence holds, and even harder to decide how to change the ontology in case the consequence is unwanted. For example, in the current version of the medical ontology SNOMED [16], the concept Amputationof-Finger

Abstract. In this paper, we propose a service for contracting axioms from ontologies based on the description logic EL. In particular, we devise algorithms that implement the contraction operation of the AGM theory on belief change. We first generalise the AGM contraction postulates to description

In a previous ICFCA paper we have shown that, in the Description Logics EL and ELgfp, the set of general concept inclusions holding in a finite model always has a finite basis. In this paper, we address the problem of how to compute this basis efficiently, by adapting methods from formal concept

and the query language that is used to describe consequences, we obtain different versions of the problem. We focus on the lightweight description logic EL as an ontology language, and consider query languages based on (i) subsumption queries, (ii) instance queries over ABoxes, (iii) conjunctive queries over

Abstract. Unification in Description Logics (DLs) has been proposed as an inference service that can, for example, be used to detect redundan-cies in ontologies. For the DL EL, which is used to define several large biomedical ontologies, unification is NP-complete. However, the unifi-cation

Unification in Description Logics (DLs) has been proposed as an in-ference service that can, for example, be used to detect redundancies in ontologies. For the DL EL, which is used to define several large biomedical ontologies, unification is NP-complete. However, the unification algorithms for EL

for terminologies given in the description logic EL extended with role inclusions and domain and range restrictions for three distinct types of queries: subsumption, instance, and conjunctive queries. In all three cases, we present polynomialtime algorithms that decide whether two terminologies give the same

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avoiding the known errors. We study error-tolerant reasoning tasks in the description logic EL. While these problems are in-tractable, we propose methods for improving the reasoning times by pre-compiling information about the known errors and using proof-theoretic techniques for computing justifications