Description Logic

Intelligent behavior usually depends on the availability of appropriate domain knowledge and the ability to draw inferences from this knowledge and observed facts. For this reason, knowledge representation and reasoning is a key subarea of Artificial Intelligence. Description Logics (DLs) are a well-investigated family of logic-based knowledge representation languages, which are frequently used to formalize ontologies for application domains such as the Semantic Web, biology and medicine, and engineering domains. The course introduces syntax and semantics of DLs as well as the relevant inference problems. It then investigates model-theoretic properties (like finite-model-property, tree-model-property, and bisimulation invariance) and computational properties (like decidablility and complexity of reasoning) both for expressive and inexpressive members of the DL family of knowledge representation languages. It also shows up a connection between query answering in databases and reasoning in DLs.