On labeling schemes for the semantic web

Abstract

This paper focuses on the optimization of the navigation through voluminous subsumption hierarchies of topics employed by Portal Catalogs like Netscape Open Directory (ODP). We a d v ocate for the use of labeling schemes for modeling these hierarchies in order to e ciently answer queries such as subsumption check, descendants, ancestors or nearest common ancestor, which usually require costly transitive closure computations. We rst give a qualitative comparison of three main families of schemes, namely bit vector, pre x and interval based schemes. We then show that two labeling schemes are good candidates for an e cient implementation of label querying using standard relational DBMS, namely, the Dewey Pre x scheme 6] and an Interval scheme by A g r a wal, Borgida and Jagadish 1]. We compare their storage and query evaluation performance for the 16 ODP hierarchies using the PostgreSQL engine.

Advances in Databases and Information Systems

“…Our encoding extends the labelling scheme presented in [2] and further investigated in [7]. In our labelling scheme the successors of each node are assumed to be linearly ordered (by their position, say from left to right), and a node in the taxonomy tree is identified by its position with respect to the parent node.…”

Backward inference and pruning for RDF change detection using RDBMS

“…On the other hand, Delta function [15, 16] computes the closure on-the-fly using a labelling scheme (e.g. interval-labelling scheme [18]). Thus, it efficiently checks the transitive closure without computing all the derived triples.…”