Class and Instance Equivalences in the Web of Linked Data: Distribution and Graph Structure

Abstract

The Web of Linked Open Data (LOD) is a decentralized effort in publishing datasets using a set of conventions to make them accesssible, notably thought RDF and SPARQL. Links across nodes in published datasets are thus critical in getting value for the LOD cloud as a collective effort. Connectivity among the datasets can occur through these links. Equivalence relationship is one of the fundamental links that connects different schemas or datasets, and is used to assert either class or instance equivalence. In this article, we report an empirical study on the equivalences found in over 59 million triples from datasets accessible via SPARQL endpoints in open source data portals. Metrics from graph analysis have been used to examine the relationships between repositories and determine their relative importance as well as their ability to facilitate knowledge discovery.