RDFS: The primary document

Shorter and more interesting than I remember.

About two years ago I wondered if RDF Schema had become merely a layer of OWL or if anyone used RDFS by itself without OWL. My theory was that because tools such as TopBraidComposer, Protege, and SWOOP that let you design RDFS vocabularies also let you assign OWL properties to your classes, people used those because they were there, and we ended up with few pure RDFS vocabularies.

Writing about the Semantic Web

And Linked Data, and RDF, and RDFa, and SPARQL, and OWL, and...

After writing a few paid articles and doing a lot of blogging about various issues, features, and trends surrounding the Semantic Web, Linked Data, RDF, RDFa, SPARQL, OWL, and related tools and implementations, I thought it would be nice if I could tie them together into something resembling a cohesive whole. So, I wrote a short essay titled RDF, The Semantic Web, and Linked Data with over 70 footnote links to these various pieces. It will be a handy reference for me in the future, and I hope it…

Adding metadata value with Pellet

A nice new feature of Pellet 2.0.

The open-source program Pellet is described as an OWL reasoner, but I’ve used it mostly as a SPARQL engine that happens to understand OWL. So, for example, if I have RDF that says “Loretta’s spouse is Leroy and spouse is a symmetric property,” but the data makes no mention of Leroy’s spouse, and I ask Pellet “who is Leroy’s spouse,” it can give me the answer.

Storing information about the meaning of terms—their “semantics”—can make data more valuable. Critics of semantic web technology consider such talk to be pie-in-the-sky AI talk; how can you encode the real meaning of words? More importantly, how can you do it in a way that programs can read and use to solve real data problems?

The "DL" in "OWL DL"

An interesting legacy that contributes many cool things to OWL.

I drive a Honda Accord EX. To even write that, I had to look at the back of my car to remember the “EX” part, because it never meant anything to me. I try to remember to mention it when I call the dealership to ask about the availability of some part, because it might matter to them, but it doesn’t to me.