Description Logics (DLs) are a successful family of logic-based knowledge representation formalisms, which can be used to represent the conceptual knowledge of an application domain in a structured and formally well-understood way. They are employed in various application domains, such as natural language processing, configuration, and databases, but their most notable success so far is the adoption of the DL-based language OWL as standard ontology language for the semantic web. This course concentrates on designing and analyzing reasoning procedures for DLs. After a short introduction of predecessor formalisms such as semantic networks and frames, it will introduce the basic features of DLs such as concepts, TBoxes and ABoxes, and basic inference problems such as the subsumption and the instance problem. The course introduces techniques for solving these problems based on tableau-algorithms, automata, and other approaches. Also, the complexity of standard DLs is analyzed, identifying expressive DLs for which reasoning is expensive in the worst case, but still manageable in practice, and lightweight DLs for which reasoning is tractable.
The lecture takes place twice a week in room E05: Tuesday 16:40-18:10 (DS6) and Thursday 16:40-18:10 (DS6).
From May 24th on, the exercise group takes place every Thursday in DS4 (13:00-14:30), Room E05, and is held by Carsten Lutz.Every week, an exercise sheet is made available for download from this webpage.