Deciding ALBO with tableau

This paper presents a tableau approach for deciding description logics outside the scope of OWL DL and current state-of-the-art tableau-based description logic systems. In particular, we define a sound and complete tableau calculus for the description logic ALBO and show that it provides a basis for decision procedures for this logic and numerous other description logics. ALBO is the extension of ALC with the Boolean role operators, inverse of roles, domain and range restriction operators and it includes full support for objects (nominals). ALBO is a very expressive description logic which is NExpTime complete and subsumes Boolean modal logic and the two-variable fragment of firstorder logic. An important novelty is the use of a versatile, unrestricted blocking rule as a replacement for standard loop checking mechanisms implemented in description logic systems. Our decision procedure is implemented in the MetTeL system. © 2007 by Bozen-Bolzano University Press.