## Query Answering Using Views for Data Integration over the
Web

**Diego Calvanese, Giuseppe De Giacomo, Maurizio Lenzerini, and
Moshe Y. Vardi**
*Proc. of the 2nd Int. Workshop on the Web and Databases
(WebDB 1999).* 1999.

Query answering using views amounts to computing the answer to a
query having information only on the extension of a set of views.
This problem is relevant in information integration over the web,
where data are typically modeled by means of semi-structured
mechanisms. We address query answering using views in a context
where both the query and the views are expressed in terms of
regular expressions (regular path queries), and denote the pairs of
objects in the database connected by a matching path. This setting
is typical in those cases where the database is conceived as a
graph, such as in semi-structured data. In particular, we study
algorithms for answering regular path queries using views under
different assumptions, namely, closed and open domain, and sound,
complete, and exact information on view extensions. We characterize
data, expression and combined complexity of the problem, showing
that the proposed algorithms are essentially optimal.

@inproceedings{WebDB-1999,
title = "Query Answering Using Views for Data Integration over the Web",
year = "1999",
author = "Diego Calvanese and De Giacomo, Giuseppe and Maurizio
Lenzerini and Moshe Y. Vardi",
booktitle = "Proc. of the 2nd Int. Workshop on the Web and Databases
(WebDB 1999)",
pages = "73--78",
}

ps.gz
pdf