1. Small is Again Beautiful in Description Logics
Franz Baader
TU Dresden, Germany

2. Semantic networks Animal Frog Green Kermit Leaf Tree [Quillian, 1967]
one of the origins
of DLs
Semantic networks
[Quillian, 1967]
Animal
IS-A
has-color
Frog
Green
IS-A
IS-A
has-color
has-part
Kermit
Leaf
Tree
sits-on

3. Problems
with Semantic Networks

4. Ambiguities
in Semantic Networks
Animal
IS-A
color
Frog
Green

5. Ambiguities
resolved in DLs
Animal
IS-A
color
Frog
Green

6. Description logic system
structure

7. Complexity
of reasoning
tractability barrier

8. Ways out of this dilemma expressive DL sound, but incomplete
tractable algorithms
expressive DL
sound and complete
intractable algorithms
inexpressive DL
sound and complete
tractable algorithms
approach followed by main-stream DL research in the last 15 years

9. Ways out of this dilemma expressive DL sound, but incomplete
tractable algorithms
expressive DL
sound and complete
intractable algorithms
inexpressive DL
sound and complete
tractable algorithms

10. Description Logics
research of the last 20 years

11. Light-weight DLs subsumption and classification tractable
sufficient expressive power for life-science ontologies

12. Value restrictions vs existential restrictions in DLs

14. Formal semantics

15. Subsumption

16. Complexity of subsumption

17. Extension

19. Extension

20. Extension

21. CEL

22. Light-weight DLs query answering using relational database systems
sufficient expressive power to capture conceptual modelling formalisms

24. Conjunctive query

25. Query answering

26. Query answering

27. Query answering

30. Questions?