Description logics (DLs) are a family of knowledge representationlanguages which can be used to represent the terminological knowledgeof an application domain in a structured and formally well-understoodway. DLs differ from their predecessors, such as semantic networks and frames, in that they are equipped with a formal, logic-based semantics, which can, e.g., be given by a translation into first-order predicate logic.
In this talk I will give an introduction to description logics by providing a fairly detailed discussion of the description logic ALC. The motivationfor focusing on ALC is that it is a good representative example of the whole family of DLs. Time permitting, I will also discuss a number of other DLs, some of which are more expressive, and some less expressive than ALC.