Wouter Beek successfully defended his thesis "The ‘K’ in ‘Semantic Web’ stands for ‘Knowledge’" at the VU. He earned cum laude PhD, which happens to only about 5% of the computer science PhDs in the Netherlands!
Wouter's work depends to a large extend on the SWI-Prolog semantic web infrastructure. He contributed with many bug reports and patiently explained all the subtle things about the relevant W3C standards to me. In addition he developed the
semweb/rdf11 library, providing a much cleaner API to deal with RDF than the original
semweb/rdf_db. Wouter's contributions made the SWI-Prolog semantic web libraries robust and standard compliant. It is now to use them for expressing knowledge!
Wouter, congratulations and thanks for the (still ongoing) collaboration!