- From: David Booth <david@dbooth.org>
- Date: Sun, 17 Mar 2013 00:26:26 -0400
- To: Alan Ruttenberg <alanruttenberg@gmail.com>
- CC: Jeremy J Carroll <jjc@syapse.com>, Umutcan ŞİMŞEK <s.umutcan@gmail.com>, Kingsley Idehen <kidehen@openlinksw.com>, "public-semweb-lifesci@w3.org" <public-semweb-lifesci@w3.org>
Hi Alan, On 03/16/2013 01:49 PM, Alan Ruttenberg wrote: > David's assertion that a uri can mean different things in different > graphs is an opinion An opinion? It is direct consequence of standard RDF Semantics! Read the spec: http://www.w3.org/TR/rdf-mt/ The RDF semantics is only defined for a *given* RDF graph. It does not constrain a URI's resource identity across *different* graphs. And here is a trivial existence proof that demonstrates that a URI does *not* necessarily denote the same resource in different graphs. Graph 1 (assuming standard owl: prefix): <http://example/h> a <http://example/WhiteHorse> . <http://example/WhiteHorse> owl:disjointWith <http://example/BlackHorse> . Graph 2: <http://example/h> a <http://example/BlackHorse> . <http://example/WhiteHorse> owl:disjointWith <http://example/BlackHorse> . Each graph (by itself) has satisfying interpretations per standard RDF (and OWL) semantics. And <http://example/h> denotes a resource in each graph. But clearly it denotes a *different* resource in each graph. > that does not concur with either the > web specifications Correct. As I pointed out, the AWWW's statement that "a URI identifies one resource" is a good goal, but it does not concur with standard RDF semantics. nor the goals they were built to satisfy. Caveat emptor. Not true! As I said before, I *agree* with the goal stated in the AWWW, that a URI should denote one resource! But that does not change the reality: that a URI does *not* necessarily denote only one resource. I also think world peace is a good goal, but it is *not* the reality. If we're going to make the semantic web work, we need to keep the goals in mind while *also* recognizing the reality. Facing reality should not be construed as dismissing the goals. We cannot simply wish the reality away. We need to do the engineering to make it work. David
Received on Sunday, 17 March 2013 04:26:54 UTC