Please assume that on this page, these declarations hold:

@prefix ex: <http://madeupexampleIsurehopethisisnotarealdomain.com/>. 
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>. 
@prefix rdfs: <namespace URI: http://www.w3.org/2000/01/rdf-schema#>. 

This is in response to Jen's concerns from class the other day (Sept 20, 2002).

One way to approach generating RDF content is to start writing lots of assertions without many, if any, machine readable constraints. For example:

ex:Bijan ex:knows ex:Sarah.}} 
 
For we human's reading this, what I intend to assert seems clear, to wit, that I know someone named Sarah (some specific Sarah). (Interestingly, I know several Sarahs, and which one ex:Sarah is supposed to refer to is unclear to me as I write this!) A RDF reasoner can figure at least the following additional statement: 
{{{ex:knows rdf:type rdf:Property.}}} 
 
But, an RDF reasoner would not detect the contradiction in the following knowledge base: 
{{{ex:Bijan ex:knows ex:Sarah. 
ex:knows ex:subClassof ex:BigCheeses.

As the RDF reasoner don't understand ex:subClassOf, it can't infer from the second statement that ex:knows is a rdfs:Class.