Database Reference
In-Depth Information
provides a uniform interface for querying collec-
tions of pre-existing data sources that were created
independently. Mediator systems are based on a
single mediated schema in terms of which users'
queries are issued and the information sources to
integrate are described. The descriptions specify
semantic relationships between the contents of the
sources and the mediated schema.A user query that
is formulated on a mediated schema is translated
into a query against local schemas using views.
Query plans are computed and executed through
wrappers in order to get the answers to the user
query. The goal is to give users the illusion that
they interrogate a centralized and homogeneous
system.
Ontology:
A model of the objects of an ap-
plication domain composed of concepts, attributes
of concepts and relations between concepts.
Reference Reconciliation:
The reference rec-
onciliation problem consists in deciding whether
different identifiers refer to the same data: i.e.,
correspond to the same world entity
UnsupervisedApproach:
An approach where
the program is not trained by some
data
that are
labeled with the desired output and which are
provided by human experts.
Wrapper:
Systems that aim at accessing a
source, extracting the relevant data and presenting
such data in a specified format.
ENDNOTES
ii
A research project funded by France Telecom
R&D (2005-2008)
ii
Another version of Cora is available at
http://www.cs.umass.edu/~mccallum/data/
cora-refs.tar.gz
Search WWH ::
Custom Search