Alice: There's this guy, "Charlie". (his blog: http://blogs.example.com/charlie.) Bob: Oh! Wow, interesting character. Do you like him?! Grant: I've heard about him. You might want to talk to Harry about him. Ivan: I actually went to High School with him. He was okay. ...
You don't need to include the full definition, or even a complete description, just a URL which readers can use to find out more. In some case (like this example), the URL serves both to disambiguate "Charlie" and to offer more information. Those could be separated:
Disambiguation via URI
Alice: There's this guy, "Charlie". (He used to have a blog at http://blogs.example.com/charlie, but it's gone now and not in any of the web archives or caches I can find.)
Information without Disambiguation
Alice: There's this guy, "Charlie". He uses http://blogs.example.com but I'm not sure which user he is there.
That information may seem useless, but it greatly narrows down the possible interpretations of "Charlie".
There are several ways to support PullTheDefinition in RDF:
Alice talks about <http://www.alice.example.com/folks#Charlie>
where http://www.alice.example.com/folks offers RDF/XML saying where his blog is.
Alice talks about <http://www.alice.example.com/folks/Charlie>
where http://www.alice.example.com/folks/Charlie gives a "303 See Other" redirect to some place which offers RDF/XML saying where Charlie's blog is.
Alice talks about <tag:firstname.lastname@example.org,2003-06-05:Charlie> and also says: <tag:email@example.com,2003-06-05:Charlie> rdfs:isDefinedBy <http://www.alice.example.com/folks>.
As an RDF consumer, can you assume every HTTP URI you see used in RDF can be dereferenced to find the definition? Does every use of an HTTP URI delegate definitional authority to the referenced site? There is no consensus on this. See NamespaceDistortion and FollowLinksForMoreInformation.
If Alice says:
<http://www.alice.example.com/folks#Charlie> hair:color hair:Blonde
while http://www.alice.example.com/folks says
<http://www.alice.example.com/folks#Charlie> hair:color hair:Black
then what should we conclude? It's not clear.
To what extent can Alice assume that folks will pull the definition? If she really wants to tell people that Charlie is six feet tall, can she just put that in the definition (linked by one of the above methods) or must she include it in every message?
Please put comments down here please, in PPR:ThreadMode