Re: Fwd: Using Statement Identifiers to Manage Provenance

Hey Graham,

On Wednesday 18 May 2011 22:56:58 Graham Klyne wrote:
> Olaf Hartig wrote:
> > Hey Graham,
> > 
> > On Wednesday 18 May 2011 11:01:17 Graham Klyne wrote:
> >> [...]
> >> My current sense is that RDF community consensus favours named graphs:
> >> (1) the SPARQL syntax makes explicit provision for querying named
> >> graphs, (2) the current RDF working group is giving consideration to
> >> including a mechanism to encode named graphs within a single RDF
> >> documemt
> >> (3) even when using RDF without named graph support, named graphs map
> >> directly to a natural web-based implementation: RDF documents
> >> retrievable from web URIs.
> >> [...]
> > 
> > I never understood this argument completely so far.
> > How exactly does this mapping you refer to work?
> 
> I assume you refer to (3) - it's simply if an RDF document is published on
> the web using a URI, then that URI can be interpreted as denoting that
> graph.  If that used in RDF statements published separately, those
> statements can be metadata (e.g. provenance) about that graph.

And that's exactly where I have the following issue with this analogy: "an RDF 
document is published on the web" is a Web resource, it's content (what we 
will see a representations when we do an HTTP GET) may change over time. 
Hence, you give a name (i.e. a URI) to something changeable. With Named 
Graphs, in contrast, we name something which is immutable: a specific set (in 
the mathematical sense) of RDF triples. This distinction may seem too subtle 
but I say that it may make a significant difference when it comes to using the 
name in statements about the named thing.

Olaf
 
> This is not always the most convenient approach.  I was just using it as an
> illustration that named graphs are not a great distance away from plain RDF
> on the web.
> 
> #g
> --

Received on Thursday, 19 May 2011 05:54:23 UTC