Path Outlines: Browsing Path-Based Summaries of Linked Open Datasets

Abstract

Linked Data (LD) are structured sources of information, such as DBpedia or Geonames, that can be linked together and queried. The information they contain is atomized into triples, each triple being a simple statement composed of a subject, a predicate and an object. Triples can then be combined to form higher level statements following information needs. This granularity makes it difficult to produce overviews of LD content. We therefore introduce the concept of path-based summaries which carries a higher level of semantics for data producers. We also introduce the tool Path Outlines to support LD producers in browsing path-based summaries of their datasets. We present its interface based on the broken (out)lines layout algorithm and the path browser visualisation. Our approach, reifying chains of statements into path outlines, was informed by the observation of LD producers and we report a characterisation of their needs. We compare Path Outlines with the current baseline technique (Virtuoso SPARQL query editor) in an experiment with 36 participants. We show that participants prefer Path Outlines, find it easier to understand, easier to use, faster, and lowering the number of tasks that users give-up before completing them.