- From: Antoine Zimmermann <antoine.zimmermann@insa-lyon.fr>
- Date: Tue, 01 Mar 2011 18:46:53 +0100
- To: Yves Raimond <Yves.Raimond@bbc.co.uk>
- CC: Nathan <nathan@webr3.org>, Andy Seaborne <andy.seaborne@epimorphics.com>, RDF WG <public-rdf-wg@w3.org>
Le 01/03/2011 18:36, Yves Raimond a écrit :
> On Tue, Mar 01, 2011 at 05:23:46PM +0000, Nathan wrote:
>> Andy Seaborne wrote:
>>> On 01/03/11 16:41, Nathan wrote:
>>>> actually ^ may be better.. such that
>>>>
>>>> :a :b :c .
>>>>
>>>> could be written as:
>>>>
>>>> :c ^:b :a .
>>>>
>>>> meaning
>>>>
>>>> :c [ owl:inverseOf :b ] :a .
>>>
>>> meaning there is a there is bnode in the predicate position.
>>>
>>>>
>>>> meaning:
>>>>
>>>> :a :b :c .
>>>>
>>>
>>> SPARQL has:
>>>
>>> :c ^:b :a .
>>>
>>> meaning
>>>
>>> :a :b :c
>>>
>>> reverses subject and object. The matching process really does swap
>>> subject and object.
>>>
>>> http://www.w3.org/TR/sparql11-query/#propertypaths
>>
>> wouldn't that require subjects as literals?
>>
>>
>
> Afaik, there is no restriction for subjects as literals in SPARQL (which explains why "abc" bif:contains "b" works, for example) - that's my biggest concern about the whole issue. Two W3C recommendations (SPARQL and RDF) are effectively contradicting each other. For example, you could generate an invalid RDF document with a perfectly valid SPARQL query (e.g. CONSTRUCT { ?name bif:contains "foo" } WHERE { ?a a foaf:Person ; foaf:name ?name . ?name bif:contains "foo" })
Well, actually more or less all sem web standards other than RDF do use
more general notions of triples (OWL 2 in the OWL 2 RL specification,
RIF and SPARQL). That's not new.
But:
"Antoine" ^foaf:names az#me .
does not contain a literal in the subject position. In that triple,
"Antoine" is really the object and az#me is the subject. The goal is
simply to introduce syntactic sugar for ease of writing (just like the
keyword "a" does not mean that there is a predicate "a" defined anywhere).
There is no problem either with the CONSTRUCT query, which is
normatively defined so that to eradicate all non-RDF triples that would
be produced from it. The output is, by definition, always a
syntactically valid RDF document.
AZ.
>
> Best,
> y
>
--
Antoine Zimmermann
Researcher at:
Laboratoire d'InfoRmatique en Image et Systèmes d'information
Database Group
7 Avenue Jean Capelle
69621 Villeurbanne Cedex
France
Lecturer at:
Institut National des Sciences Appliquées de Lyon
20 Avenue Albert Einstein
69621 Villeurbanne Cedex
France
antoine.zimmermann@insa-lyon.fr
http://zimmer.aprilfoolsreview.com/
Received on Tuesday, 1 March 2011 17:47:28 UTC