Article details

Research area
Natural language & AI

The 17th International Semantic Web Conference, Asilomar, California


Peter Patel-Schneider, Axel Polleres, David Martin

Fixing Comparative Preferences for SPARQL


Sometimes one does not want all the solutions to a query but instead only
those that are most desirable according to user-specified preferences. If a
user-specified preference relation is acyclic then its specification and
meaning are straightforward. In many settings, however, it is valuable to
support preference relations that are not acyclic and that might not even be
transitive, in which case though their handling involves some open
questions. We discuss a definition of desired solutions for arbitrary
preference relations and show its desirable properties. We modify a
previous extension to SPARQL for simple preferences to correctly handle any
preference relation and provide translations of this extension back into
SPARQL that can compute the desired solutions for all preference relations
that are acyclic or transitive. We also propose an additional extension
that returns solutions at multiple levels of desirability, which adds
additional expressiveness over prior work. However, for the latter we
conjecture that an effective translation to a single (non-recursive) SPARQL
query is not possible.

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