Description Logic

Dr. (habil.) 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. It will introduce the basic features of DLs, e.g., 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 tableaux 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 ends with a section on qualitative extensions of DLs.


The lecture takes place twice a week. Additionally, there is a weekly exercise session held by İsmail İlkan Ceylan. Exercise sheets will be available approximately one week before the session.

The lectures and the exercise sessions will take place in room E005 at the following times: The exact distribution of lectures and exercise sessions can be found in the table below.

Monday Tuesday Thursday
10 Oct. to 14 Oct. Lecture Lecture
17 Oct. to 21 Oct. Exercise session (exercise sheet 1) Lecture Lecture
24 Oct. to 28 Oct. Exercise session (exercise sheet 2) Lecture Lecture
31 Oct. to 4 Nov. (reformation day) Lecture Lecture
7 Nov. to 11 Nov. Exercise session (exercise sheet 3) Lecture Lecture
14 Nov. to 18 Nov. Exercise session (exercise sheet 4) Lecture Lecture
21 Nov. to 25 Nov. Exercise session (exercise sheet 5) Lecture Lecture
28 Nov. to 2 Dec. Exercise session (exercise sheet 6) Lecture Lecture
5 Dec. to 9 Dec. Lecture Lecture Exercise session (exercise sheet 7)
12 Dec. to 16 Dec. Exercise session (exercise sheet 8) Lecture Lecture
19 Dec. to 23 Dec. Exercise session (exercise sheet 9) Lecture (christmas holidays)
2 Jan. to 6 Jan. (christmas holidays) (christmas holidays) Lecture
9 Jan. to 13 Jan. Exercise session (exercise sheet 10) Lecture Lecture
16 Jan. to 20 Jan. Exercise session (exercise sheet 11) Lecture Lecture
23 Jan. to 27 Jan. Exercise session (exercise sheet 12) Lecture Lecture
30 Jan. to 3 Feb. Exercise session (exercise sheet 13) 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: