The lecture ends on the 7th of July. On that day the last session is a
question and answers session, where students can ask about the things
presented in the lecture. Questions that are send to me
(turhan[at]tcs.inf.tu-dresden.de) per email in advance, are preferred.
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 analyzing 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 analyzed,
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 in room E05: Tuesday and Thursday always at
The first exercise takes place on Wednesday 6th of April. The exercise
sessions are held by Felix Distel on
Wednesdays 14:50-16:20 (DS5) in Room E05. Every week, an exercise
sheet is made available for download from this webpage from the table
A script of the lecture is not available and students are strongly
recommended to copy what is written on the blackboard.
We provide the slides for the introductory sessions:
We also provide scanned versions of the example slides used in the session about frames and semantic networks:
Credits / Examinations
students can earn 9 credits by attending this lecture. The lecture can
be used for the modules KRAI, IT, TCSL. In order to get the credits,
CL students have to meet both of the following two obligations:
Computer Science students are not obliged to present exercises, but
are invited to do so.
- present at least four exercises in front of the exercise group;
- pass an oral examination at the end of the term.
- F. Baader, D. Calvanese, D. McGuinness, D. Nardi, and
P. F. Patel-Schneider, editors. The Description Logic Handbook:
Theory, Implementation, and Applications. Cambridge University
- 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.
- Franz 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.