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Re: Use cases wrt Dataset proposal (UC 1.5, UC 5.2)

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Wed, 29 Feb 2012 16:43:36 +0100
Message-ID: <4F4E47A8.3070107@emse.fr>
To: Pat Hayes <phayes@ihmc.us>
CC: RDF WG <public-rdf-wg@w3.org>


Le 29/02/2012 16:27, Pat Hayes a écrit :
>
> On Feb 29, 2012, at 8:43 AM, Antoine Zimmermann wrote:
>
>> *Beware*: this is about design solutions using the dataset proposal
>> as a whole. It is not strictly related to the semantics. It
>> explains concretely how one could store things in a dataset,
>> possibly entail new things according the dataset semantics of [2]
>> and so on, such that eventually it addresses the use case. So it
>> contains a number of things that applications should do to address
>> the UCs, independently of the truth values of triples or "named"
>> graphs.
>>
>>
>> UC 1.5: Exchanging the contents of RDF stores
>>
>> This is trivial. RDF stores mostly implement SPARQL datasets, so it
>> suffices to have a serialisation syntax for datasets. It does not
>> matter what the semantics is. TriG or N-Qauds will do.
>>
>>
>> UC 5.2: OWL's “Ontology Documents”
>>
>> Currently, OWL imports statement means that an OWL processor should
>> fetch wathever document it founds when "accessing" the imported URI
>> (using whatever protocol it needs, see [1]). This behaviour is
>> independent of the formal semantics of OWL ontologies. It's an
>> operation that must be done prior to any interpretation of the
>> ontology.
>>
>> If multiple ontologies are stored in a dataset, it seems reasonable
>> to use the import mechanism offline, where instead of a HTTP
>> lookup, the system directly fetches from the corresponding "named"
>> graph.
>
> Whoa. I dont think this is at all reasonable. This changes the
> meaning of owl:imports, in effect (or extends it in a new way). After
> all, the URIs used as labels in a datastore might *refer* to
> anything, and in particular, they might refer to a different ontology
> stored somewhere on the web identified by an http URI. So the meaning
> of an imports might change when the ontology containing it is put
> into a dataset and taken offline.

owl:imports is a strange beast, and the OWL specs allows things with 
this predicate that you are possibly not imagining. It truly is what I 
say: you take the URI (as a syntactic element), you apply whatever 
protocole you want to apply to GET something, and what you get is 
considered to be an ontology document that you have to parse.

If I say in an ontology document:

<>  owl:imports  <http://zimmer.aprilfoolsreview.com/antoine#me> .

then, what I get, according to the OWL specs, is an ontology with the 
content of http://zimmer.aprilfoolsreview.com/antoine included, in spite 
of <http://zimmer.aprilfoolsreview.com/antoine#me> denoting a foaf:Person.

Please take a look at the OWL 2 spec section 3.2 to check.



>
> At the very least, if we mandate this, then we need to clarify the
> semantic role of "label" URIs in datasets.
>
> Pat
>
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-- 
Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
France
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http://zimmer.aprilfoolsreview.com/
Received on Wednesday, 29 February 2012 15:44:06 UTC

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