Peter Patel-Schneider gave this talk at Google January, 2006.

Peter Patel-Schneider has an interesting perspective: while he has been very involved with Semantic Web technologies like OWL and descriptive logic reasoners (author of the Classic system), he also appears to have a reasonable amount of skepticism. His talk is good because he starts off clearly explaining RDF, RDFS, and the improved formalism and expressiveness of OWL. I especially enjoyed his summarization of different types of logic, what their computational limitations and capabilities are.

I have mixed feeling about trying to implement the Semantic Web using a formal semantically rich language like OWL: I am concerned that encoding information in OWL simply takes too much effort. At the other end of the complexity spectrum, tagging is a very light weight expression of the Semantic Web but tagging is inadequate (but easy enough that many people make the effort).

I have a short list of Semantic Web resources that I find useful.