Showing papers by "Franz Baader published in 2006"

CEL: a polynomial-time reasoner for life science ontologies

Abstract: CEL (Classifier for ${\mathcal{E}{L}}$) is a reasoner for the small description logic ${\mathcal{E}{L}}^+$ which can be used to compute the subsumption hierarchy induced by ${\mathcal{E}{L}}^+$ ontologies. The most distinguishing feature of CEL is that, unlike all other modern DL reasoners, it is based on a polynomial-time subsumption algorithm, which allows it to process very large ontologies in reasonable time. In spite of its restricted expressive power, ${\mathcal{E}{L}}^+$ is well-suited for formulating life science ontologies.

CEL : A polynomial-time reasoner for life science ontologies

Abstract: CEL (Classifier for eL) is a reasoner for the small description logic ∈L + which can be used to compute the subsuinption hierarchy induced by eL + ontologies. The most distinguishing feature of CEL is that, unlike all other modern DL reasoners, it is based on a polynomial-time subsumption algorithm, which allows it to process very large ontologies in reasonable time. In spite of its restricted expressive power, eL+ is well-suited for formulating life science ontologies.

Efficient Reasoning in EL

Abstract: The early dream of a description logic (DL) system that offers both sound and complete polynomial-time algorithms and expressive means that allow its use in real-world applications has since the 1990ies largely been considered to be a pipe dream. This was, on the one hand, due to complexity results showing intractability even in very inexpressive DLs [5], in particular in the presence of TBoxes [13]. On the other hand, many of the applications considered then required more expressive power rather than less, which led to the development of more and more expressive DLs. The use of such intractable DLs in applications was made possible by the fact that highly-optimized tableau-based reasoners for them behaved quite well in practice. However, more recent developments regarding the EL family of DLs have shed a new light on the realizability of this dream. On the one hand, theoretical results [1, 6, 2] have shown that reasoning in EL and several of its extensions remains tractable in the presence of TBoxes and even of general concept inclusions (GCIs). On the other hand, it has turned out that, despite its relatively low expressivity, the EL family is highly relevant for a number of important applications, in particular in the bio-medical domain: for example, medical terminologies such as the Systematized Nomenclature of Medicine (Snomed) [9] and the Galen Medical Knowledge Base (Galen) [14] are formulated in EL or small extensions thereof, and the Gene Ontology (Go) [8] used in bioinformatics can also be viewed as an EL TBox. In this paper, we address the question of whether the polynomial-time algorithms for reasoning in EL and its extensions really behave better in practice than intractable, but highly-optimized tableau-based algorithms. To this end, we have implemented a refined version of the algorithm described in [2] in our

A new combination procedure for the word problem that generalizes fusion decidability results in modal logics

Abstract: Previous results for combining decision procedures for the word problem in the non-disjoint case do not apply to equational theories induced by modal logics-which are not disjoint for sharing the theory of Boolean algebras. Conversely, decidability results for the fusion of modal logics are strongly tailored towards the special theories at hand, and thus do not generalize to other types of equational theories. In this paper, we present a new approach for combining decision procedures for the word problem in the non-disjoint case that applies to equational theories induced by modal logics, but is not restricted to them. The known fusion decidability results for modal logics are instances of our approach. However, even for equational theories induced by modal logics our results are more general since they are not restricted to so-called normal modal logics.

Reasoning Support for Ontology Design.

Abstract: The design of comprehensive ontologies is a serious challenge. Therefore, it is necessary to support the ontology designer by providing him with design methodologies, ontology editors, and automated reasoning tools that explicate the consequences of his design decisions. Currently, reasoning tools are largely limited to the reasoning services (i) computing the subsumption hierarchy of the classes in an ontology and (ii) determining the consistency of these classes. In this paper, we survey the most important tasks that arise in ontology design and discuss how they can be supported by automated reasoning tools. In particular, we show that it is beneficial to go beyond the usual reasoning services