The Rewriting Algorithm for Disjunctive Queries between Peer Ontologies
Biao Qin · Third International Conference on Semantics, Knowledge and Grid (SKG 2007) · 2007
We study the problem of answering queries given a set of mappings between peer ontologies. In addition to the schema mapping between peer ontologies, there are axioms to give constraints to classes and properties. We propose a set of rules to build graphs for the axioms. Because the axioms have different properties, the generated graphs are classified into four sets. In each peer, its RDF/OWL query languages can support regular expressions. If it wants to be transitive along semantic paths in peer knowledge man- agement systems, we must rewrite conjunctive and disjunc- tive queries between peers. Because conjunctive queries are well-understood, we focus on a novel algorithm to rewrite disjunctive queries along semantic paths based on the graphs. For all atoms of a disjunctive query, we con- sider its union as a set and find the maximum rewritings over peers through a graphical way. Finally we do exten- sive simulation experiments. The simulation results show our algorithm can generate more rewritings than the naive rewriting algorithm at each distance.