Description Logics for Data Access

Tutorial at the 24th AAAI Conference on Artificial Intelligence (AAAI 2010)
Atlanta, Georgia, U.S.A., July 11-15, 2010

Giuseppe De Giacomo      Domenico Lembo

Dipartimento di Informatica e Sistemistica
Università di Roma ''La Sapienza''

Tutorial description

The tutorial illustrates recent developments in Description Logics (DLs) aimed at coupling DL knowledge bases with relational data stores. For this coupling to be effective, two main issues need to be addressed: (i) The language used to query the knowledge base needs to be much more expressive than DL expressions, in particular the ability of expressing arbitrary joins as in conjunctive queries (CQs) studied in databases is essential; (ii) Query answering should remain tractable (PTIME or less) with respect to the size of the data. In order to address such issues, as often happens in DL research, the language used to specify the knowledge base has to be carefully designed to suitably balance expressiveness and computational complexity of reasoning. However, differently from what typically happens in DL research, reasoning is not based on firstorder/ modal tableaux, but on chase techniques originally developed in databases for reasoning over data dependencies. We will discuss DL languages designed for data access, and techniques for reasoning in such DLs, focusing specifically on query answering. We also illustrate reasoning tools that are available for such logics.

General info

Time: Monday, July 12, 2:00 PM 6:00 PM

Presentation style: Lectures with slides and demonstration

Target audience: Researchers, Ph.D. Students, and Practitioners

Prerequisite knowledge: Basic knowledge in first-order logic and relational databases. Background in Description Logics is preferable, but not strictly necessary.

Outline of the tutorial content (draft)

  1. Introduction to the theory of conjunctive queries over relational databases
  2. DL knowledge bases and incomplete information
  3. Conjunctive query answering in DLs
  4. The DL-Lite family
  5. Query answering in the DL-Lite family: Compiling the knowledge base into the query
  6. DL-Lite for data integration: Accessing external data sources through mappings
  7. Approaches based on pre-processing of the data sources
  8. Beyond conjunctive queries: An Epistemic query language

Main Reference

Notes on DL-Lite.

Which is also available as the paper:

D. Calvanese, G. De Giacomo, D. Lembo, M. Lenzerini, A. Poggi, M. Rodriguez-Muro, and Riccardo Rosati. Ontologies and databases: The DL-Lite approach. In Sergio Tessaris and Enrico Franconi, editors, Semantic Technologies for Informations Systems - 5th Int. Reasoning Web Summer School (RW 2009), volume 5689 of Lecture Notes in Computer Science, pages 255-356. Springer, 2009.

Related Links

AAAI-10 Tutorial Forum web page

Last modified: July 12, 2010