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Combining knowledge representation and reasoning formalisms is an important and challenging task. It is important because non-trivial AI applications often comprise different aspects of the world, thus requiring suitable combinations of available formalisms modeling each of these aspects. It is challenging because the computational behavior of the resulting(More)
Motivated primarily by medical terminology applications, the prominent DL SHIQ has already been extended to a DL with complex role inclusion axioms of the form R • S ˙ R or S • R ˙ R, called RIQ, and the SHIQ tableau algorithm has been extended to handle such inclusions. This paper further extends RIQ and its tableau algorithm with important expressive(More)
We investigate the expressive power and computational properties of two different types of languages intended for speaking about distances. First, we consider a first-order language FM the two-variable fragment of which turns out to be undecidable in the class of distance spaces validating the triangular inequality as well as in the class of all metric(More)
1 Motivation Combining description logics (DLs) with other logical formalisms, including other DLs, is an important and challenging task. Recent examples include: 1. the combination of DLs with temporal logics to form multi-dimensional temporal DLs, cf. e.g. [1, 6, 10]; 2. the fusion of multiple DLs into a single formalism that inherits decidability from(More)
abstract. We introduce a new semantics for modal predicate logic, with respect to which a rich class of first-order modal logics is complete, namely all normal first-order modal logics that are extensions of free quantified K. This logic is defined by combining positive free logic with equality PFL. = and the propo-sitional modal logic K. We then uniformly(More)
We present a general framework for the design of formal on-tologies, resting on two main principles: firstly, we endorse Rudolf Car-nap's principle of logical tolerance by giving central stage to the concept of logical heterogeneity, i.e. the use of a plurality of logical languages within one ontology design. Secondly, to structure and combine heterogeneous(More)