Description Logics

Dr.-Ing. Anni-Yasmin Turhan

Course Description

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 analysing 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 analysed, 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. Additionally, there is a weekly exercise session held by Marcel Lippmann. Exercise sheets will be available approximately one week before the session.

The lectures and the exercise sessions will take place in room E05 at the following times: Tuesdays 16.40–18.10, Wednesdays 14.50–16.20, and Thursdays 16.40–18.10. The exact distribution of lectures and exercise sessions can be found in the table below.

There is a mailing list for discussing organisational and technical issues of the course.

Tuesday Wednesday Thursday
8 Oct. to 12 Oct. Lecture Exercise session
(Exercise sheet 1)
15 Oct. to 19 Oct. Lecture Exercise session
(Exercise sheet 2)
22 Oct. to 26 Oct. Exercise session
(Exercise sheet 3)
Lecture Lecture
29 Oct. to 2 Nov. Exercise session
(Exercise sheet 4)
Public Holiday Lecture
5 Nov. to 9 Nov. Lecture Exercise session
(Exercise sheet 5)
12 Nov. to 16 Nov. Lecture Exercise session
(Exercise sheet 6)
19 Nov. to 23 Nov. Exercise session
(Exercise sheet 7)
Public Holiday Lecture
26 Nov. to 30 Nov. Lecture Exercise session
(Exercise sheet 8)
3 Dec. to 7 Dec. Lecture Exercise session
(Exercise sheet 9)
10 Dec. to 14 Dec. Lecture Exercise session
(Exercise sheet 10)
17 Dec. to 21 Dec. Exercise session
(Exercise sheet 11)
Lecture Lecture
7 Jan. to 11 Jan. Exercise session
(Exercise sheet 12)
14 Jan. to 18 Jan. Lecture Lecture
21 Jan. to 25 Jan. Exercise session
(Exercise sheet 13)
Lecture Lecture
28 Jan. to 1 Feb. Exercise session
(Exercise sheet 14)
Lecture Lecture


SWS: 4/2/–

This course can be used in the following modules:

Lecture Material

A script of this lecture is not available, and students are strongly recommended to copy what is written on the blackboard.

We provide, however, the slides for the introductory sessions: Also, we provide scanned versions of the example slides used in the session about frames and semantic networks: