[topicmapmail] Identities and names (WAS - A somewhat new topic maps format)

[Peter P. Jones]

On 7 Aug 2003 at 19:26, Peter P. Jones wrote:

> On 7 Aug 2003 at 15:08, Murray Altheim wrote:
> 
> [...]
> > 
[...]
> 
> (Not including Steve Pepper's argument for distinguishing subject
> location from mere resource location where unaddressable containments
> are an issue...) The only weak argument I can raise about the RDF
> approach as yet is the following: a) The set of names is infinite. b)
> The set of URIs (as a subset of names) is smaller but also infinite.
> c) The set of resolvable URIs is likely to remain countably finite. d)
> Therefore, given finite time and processing power isn't it better to
> have someway of distinguishing the set of resolvable addresses in
> advance? Problem: How do you know that a URI is resolvable in advance?
> Answer: Indicate that it should be. It will at least provide some
> help.
> 
> I've many pages of spec to go yet though, so maybe there's something
> covering that later on(?).
Thought so. There's an interesting paragraph in Section 1.4 of the 
RDF Semantics WD. To quote:

"If the vocabulary of an RDF graph contains URI references that are 
not in the vocabulary [[PPJ ed. note: think that should be 'set of 
resources' or 'universe']] of an interpretation I - that is, if I 
simply does not give a semantic value to some name that is used in 
the graph - then these truth conditions will always yield the value 
false for some triple in the graph, and hence for the graph itself. 
Turned around, this means that any assertion of a graph implicitly 
asserts that all the names in the graph actually refer to something 
in the world. ..."

So beware of just making up URIs that don't resolve to anything.

> 
> -- 
> Peter
> 
> 
> 
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