Affiliations: Department of Computer Science, Concordia University,
1515 St. Catherine St. West, Montreal, Quebec H3G 1M8, Canada.
grahne@cs.concordia.ca | Department of Computer Science, University of Victoria,
PO Box 3055, STN CSC, Victoria, BC V8W 3P6, Canada. thomo@cs.uvic.ca | Department of Computer Science, University of Victoria,
PO Box 3055, STN CSC, Victoria, BC V8W 3P6, Canada. wwadge@cs.uvic.ca
Note: [] Address for correspondence: Department of Computer Science,
University of Victoria, PO Box 3055, STN CSC Victoria, BC, Canada V8W 3P6
Abstract: In this paper, we introduce preferential regular path queries. These
are regular path queries whose symbols are annotated with preference weights
for "scaling" up or down the intrinsic importance of
matching a symbol against a (semistructured) database edge label. Annotated
regular path queries are expressed syntactically as annotated regular
expressions. We interpret these expressions in a uniform semiring framework,
which allows different semantic interpretations for the same syntactic
annotations. For our preference queries, we study three important aspects: (1)
(progressive) query answering (2) (certain) query answering in LAV
data-integration systems, and (3) query containment and equivalence. In all of
these, we obtain important positive results, which encourage the use of our
preference framework for enhanced querying of semistructured databases.
