W3C home > Mailing lists > Public > public-rdf-wg@w3.org > February 2012

Re: Islands (ACTION-148)

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Tue, 28 Feb 2012 18:50:13 +0100
Message-ID: <4F4D13D5.3040200@emse.fr>
To: public-rdf-wg@w3.org
As it is good to get down to earth with use cases, I'll start with the 
following case:

[2] would simply consider the 2 graphs to be independent because 
possibly, you do not trust :g3 and it's a malevolant piece of RDF. So, 
there would not much entailment, even assuming OWL entailment inside 
each graphs.

However, if an application is using an internal ontology which happens 
to contain the triple :

:age a :FunctionalProperty .

that application may decide that it must be merged with any other graphs 
it indexes. Then the same application meets a document with the triple :

:Joe :age 10 .

It mints a URI to put it in a "named" graph (say, :g1) then it meets 
another graph later on:

:Joe :age 20 .

It mints a new URI (say :g2). Since the application already have its 
internal ontology which it decides to merge with any graph, the 
following dataset will be contained in that app RDF store:

:g1 { :Joe :age 10 . :age a :FunctionalProperty .}
:g2 { :Joe :age 30 . :age a :FunctionalProperty .}

This leads to a lot of duplication of course, but it's trivial to 
optimise this without repetition. Then you have both assertional data 
and terminological data in the same "named" graph, so you can do useful 
inferences, which won't affect consistency globally.


Le 28/02/2012 17:51, Andy Seaborne a écrit :
> On 28/02/12 16:41, Ivan Herman wrote:
>> On Feb 28, 2012, at 17:19 , Andy Seaborne wrote:
>>> Pat,
>>> The fact you can have
>>> :g1 { :Joe :age 10 }
>>> :g2 { :Joe :age 30 }
>>> :g3 { :age a :FunctionalProperty }
>>> is the point. It's not about graph consistency until the app
>>> decides
>>> it wishes to apply RDF machinery to some combination of :g1 :g2 and :g3.
>>> How it does that is not spec'ed - it would be nice if it were, but given
>>> timescales, state of the art, etc, it's where the deployed semweb
>>> currently is.
>> But this also means that [2] does not work for that case, right? The
>> 'right' way, according to [2], would be to add the func. property triple
>> into both :g1 and :g2.
> Pat's example was 3 different graphs. An app can decide to use the :g3
> ontology is useful and that it thinks :g1 and :g2 have used it
> correctly. It can then use it with :g1 or on :g2 if it wants. Using on
> :g1 union :g2 is not good. This is a decision the app makes before the
> formal systems kick in.
> Andy
>> Ivan
>> [2] http://www.w3.org/2011/rdf-wg/wiki/TF-Graphs/RDF-Datasets-Proposal

Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
Tél:+33(0)4 77 42 83 36
Fax:+33(0)4 77 42 66 66
Received on Tuesday, 28 February 2012 17:50:19 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 22:02:03 UTC