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Re: Minimal dataset semantics

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Fri, 24 Aug 2012 12:48:16 +0200
Message-ID: <50375BF0.8030406@emse.fr>
To: public-rdf-wg@w3.org
Is it the resource denoted by the IRI, or is it the IRI that is 
associated with the graph?

Consider the following, IMHO realistic, example:

ex:url1 and ex:url2 are the URLs RDF Documents found on the Web. The 
dafult graph is used to put mappings between different graphs.

# EXAMPLE BEGINS #
ex:url1  owl:sameAs  ex:url2 .
ex:url1 { ex:url1  foaf:mbox  <mailto:frank@sinatra.net>}
ex:url2 { ex:url2  foaf:mbox  <mailto:frank@sinatra.net>}
# EXAMPLE ENDS #

(I don't want to hear that this incorrect according to httpRange14. 
httpRange14 is not part of RDF and, in any case, this example shows 
something that happens on the Web for real.)

Now, if it's the resource that is associated with the graph, then we 
have a resource associated with two graphs. Why not, but then it becomes 
ambiguous when you talk about the graph associated with a resource. 
Which graph? Do you talk about both graphs all the time.

I think that, in conversation, when we say "the graph associated with 
ex:url1", we tend to mean whatever is in the curly brackets after the 
IRI rather than an RDF graph that is supposed to be attached to a thing 
in the world.

We can put IRIs in the interpretation, because IRIs are not only part of 
the syntax, they are also made part of the semantics by being the 
literal values of literals with datatype IRI xsd:anyURI.

Anyway, this idea of having <i,G> pairs in the interpretation should be 
formalised as it may be a solution that avoids putting several RDF 
interpretations into one Dataset interpretation.


--AZ.


Le 23/08/2012 21:43, Richard Cyganiak a écrit :
> On 23 Aug 2012, at 19:02, Pat Hayes wrote:
>>>> b) to define a minimal version of a
>>>> "truth-based"/"entailment-based" semantics (where [[ :i1 { G }
>>>> ]] entails [[ :i1 { G' } ]] if graph G entails graph G').
>>
>> Which means that the "name" refers to the entailment closure of the
>> graph, rather than the graph itself. Right?
>
> I'm not sure what you mean by "refers to".
>
> Regarding the formal mechanism of associating IRIs with their
> respective graphs, I've started to like the idea that Alan mentioned
> the other day: Dataset interpretations contain a mapping from
> resources to graphs, called the graph extension. This mapping
> associates graphs with (some) resources. A name-graph-pair (a.k.a.
> abstract named graph)<i,G>  satisfies a dataset interpretation I if
> the graph extension in I of I(i) entails G.
>
> If I'm not messing up, then this mechanism works the same as the
> property extension and class extension mechanisms that already exist
> in RDF Semantics.
>
> So, the graph IRI then *denotes* a resource (one that is in the
> domain of the class extension function). And in the abstract syntax,
> the graph IRI is "associated" or "paired" with a certain RDF graph. I
> don't know if one can say that the IRI "refers to" the entailment
> closure of the graph.
>
> Does this make any sense?
>
> Best, Richard
>

-- 
Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
France
Tél:+33(0)4 77 42 66 03
Fax:+33(0)4 77 42 66 66
http://zimmer.aprilfoolsreview.com/
Received on Friday, 24 August 2012 10:48:56 UTC

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