Reading time: 7 - 13 minutes
In any Knowledge Graph-based project, keeping track of where data comes from is important. When you know the source of your facts or assertions, you can contextualize those facts: how relevant is assertion X to my current research, is it from a source that I personally trust, and if I have two conflicting views how can I decide which source to go with? Apart from issues of trust and confidence, tracking the source also can serve more mundane goals, such as knowledge graph maintenance: source X has published a new edition of their data set, so we need to replace the relevant data in our own Knowledge Graph, and so on.
Keeping track of the source of data is often referred to as provenance. In this blog post, we will look at provenance tracking in RDF Knowledge Graphs using the Wikidata dataset as an example, and we will look at how RDF-star and SPARQL-star, two new community efforts to extend the RDF model, can make this task easier.
Reading time: 6 - 11 minutes
The SPARQL default graph is a concept that can confuse even frequent SPARQL users. In this article, we will go over what the default graph actually is, why it seems to be something different in every RDF database, and how you can come to grips with those differences and query with confidence.