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Talk Announcement: Relational, XML, and RDF Query Reformulation, by Prof. Val Tannen

The Database & Artificial Intelligence Group of the Information Systems Institute
invites to the following talk:

Val Tannen
University of Pennsylvania

Date: Monday November 21, 2005

Time:  11:30 - 12:30

Place: Seminarroom 184/2 (DBAI), Favoritenstraße 9-11/1842, 3rd floor
(when you leave the elevator turn left, go through the corridor, the entrance is on the right side)

Title: Relational, XML, and RDF Query Reformulation



For the relational data model there exists a rich and interesting
theory of conjunctive queries and of the containment-expressing
constraints corresponding to them. Query containment under
constraints was studied during the classical times of relational
database theory using the constraints as rewrite rules in a technique
called _chase_.

Relational query reformulation, in particular certain forms of very
useful optimization, can also be handled under constraints, using
a new chase-and-backchase algorithm that we have developed.

It turns out that this relational tool can also be used to solve query
reformulation problems when XML and RDF are used (RDF is the
data model adopted in the "Semantic Web").

Most of this work is joint with Alin Deutsch (UC San Diego) and
Lucian Popa (IBM Almaden). The rest is joint with Vassilis Christophides
and his collaborators at FORTH and Univ. of Crete.