- From: Pat Hayes <phayes@ai.uwf.edu>
- Date: Fri, 12 Oct 2001 12:05:30 -0500
- To: "Seth Russell" <seth@robustai.net>
- Cc: www-rdf-rules@w3.org
> Drew McDermott said: > > Okay, if you change Sandro's "document scope" > to "graph scope," you're right. But then a rule like > > (R1 ?x ?y) |- (R2 ?y ?x) > > becomes unstatable, because the ?x and ?y in > the graph on the left are different variables from the > ?x and ?y in the graph on the right. > > Unless I'm missing something. > >Well, If I understand RDF graphs, I think you are. Don't forget every term >(variable or not) has to be a URI in a RDF graph. No! Blank nodes and literals are not URIs in an RDF grpah. The distinction is important for just this reason. bNode identifiers in an N-triples document are local to the document and do not have global scope. > But if we scope formulas >to a context (a collection of statements) the ?x ?y in the left hand of the >formula become *the same* as the ?x ?y on the right .... that's the way RDF >works .... doesn't it ? Nope, because RDF doesn't have contexts. (There are things like this in N3, but then N3 goes beyond RDF.) The graph-merging rules described in section 3 of the RDF MT document should make this clear: if you merge two RDF graphs then you *must* merge nodes with the same URI, but you *must not* merge blank nodes. Pat -- --------------------------------------------------------------------- IHMC (850)434 8903 home 40 South Alcaniz St. (850)202 4416 office Pensacola, FL 32501 (850)202 4440 fax phayes@ai.uwf.edu http://www.coginst.uwf.edu/~phayes
Received on Friday, 12 October 2001 13:05:33 UTC