Description Logic

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:

• Mondays 11.10–12.40 (exercise),
• Tuesdays 16.40–18.10 (lecture), and
• Thursdays 16.40–18.10 (lecture).

The exact distribution of lectures and exercise sessions can be found in the table below.

Announcements:

• The lecture will start on Tuesday 11 October.
• The exercise sessions will start on 17 October.

	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:

• Bachelor-Studiengang Informatik: INF-B-510 (Vertiefung), INF-B-520 (Vertiefung zur Bachelor-Arbeit)
• Master/Diplom-Studiengang Informatik: INF-BAS6 (Theoretische Informatik), INF-VERT6 (Theoretische Informatik)
• Master in Computational Logic: MCL-TCSL (Theoretical Computer Science and Logic), MCL-PI (Principles of Inference), MCL-KR (Knowledge Representation)
• Diplom-Studiengang Informatik (Studienordnung 2004): Fachgebiet Theorie der Programmierung, Fachgebiet Intelligente Systeme

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:

• Motivation and Chapter 2
• Chapter 3 and 4

• F. Baader, D. Calvanese, D. McGuinness, D. Nardi, and P. F. Patel-Schneider, editors. The Description Logic Handbook: Theory, Implementation, and Applications. Cambridge University Press, 2003.
• F. Baader and C. Lutz. Description Logic. In P. Blackburn, J. van Benthem, and F. Wolter, editors, The Handbook of Modal Logic, pages 757–820. Elsevier, 2006.
• F. Baader. Description Logics. In Reasoning Web: Semantic Technologies for Information Systems, 5th International Summer School 2009, volume 5689 of Lecture Notes in Computer Science, pages 1–39. Springer-Verlag, 2009.