Efficient Labelling

On Labeling Schemes for the Semantic Web "...we are interested in labeling schemes for RDF/S class (or property) hierarchies allowing us to efficiently evaluate descendant/ancestor, adjacent/sibling queries, as well as, finding nearest common ancestors (nca) by using only the generated labels. Compared to the transitive closure evaluation reported in our previous work [14], the performance gains for these queries are of 3-4 orders of magnitude when using adequate labeling schemes! Then, starting from a topic somewhere in the taxonomy, a user can easily and efficiently access not only its father/children (as in existing Portals) but also the leaf topics underneath where most of the web resources are classified, discover sibling topics (where related web resources may be found) or even continue navigation from the nca of two topics in the hierarchy."