Hi Jean-Baptiste,
Your observation is correct. This is because a single Wikidata statement
(with one Wikidata property) does not translate into a single triple
(with one RDF property) in RDF. Rather, several RDF triples are used,
they need to use more than one property, and these properties have
different declarations (e.g., some are DatatypeProperties and some are
ObjectProperties). Therefore, we create property variants, currently by
appending letters like "s".
The current RDF encoding is documented in our ISWC 2014 paper:
https://ddll.inf.tu-dresden.de/web/Inproceedings4005/en
You are still right that there is a problem here in that you cannot get
from "P123s" to "P123" in the current RDF. This is being worked on:
https://github.com/Wikidata/Wikidata-Toolkit/issues/84
The dumps will hopefully have this soon.
Regards,
Markus
On 08.04.2015 12:05, Jean-Baptiste Pressac wrote:
Hello,
Thank you for this initiative.
However, there is a little problem with the Properties on the result
pages. For instance on the result page of this query
http://wikisparql.org/sparql?query=DESCRIBE+%3Chttp%3A//www.wikidata.org/en…
all Wikidata properties have an extra letter after the property ID, for
instance P463 <https://www.wikidata.org/wiki/Property:P463> has an extra
"s" (P463s) so that the link to this property (on the arrow icon) leads
to a bad request page.
A click on this link :
http://www.wikidata.org/entity/P463s
Brings you on this page rather than
http://www.wikidata.org/entity/P463.
There is also a problem with the link to the wikidata ontology on this
page
http://wikisparql.org/sparql?query=DESCRIBE+%3Chttp%3A//www.wikidata.org/en….
For instance time precision has a link to
http://www.wikidata.org/ontology#timePrecision which does not exists.
Cheers,
Jean-Baptiste Pressac
Traitement et analyse de bases de données
Production et diffusion de corpus numériques
Centre de Recherche Bretonne et Celtique
Unité mixte de service (UMS) 3554
20 rue Duquesne
CS 93837
29238 Brest cedex 3
tel : +33 (0)2 98 01 68 95
fax : +33 (0)2 98 01 63 93
Le 23/03/2015 12:51, Marco Fossati a écrit :
Hi everyone,
I'd just like to announce another experimental Wikidata SPARQL
endpoint [1], kindly provided by the folks at SpazioDati [2].
It contains both the simplified and the complete dumps, as per [3].
Each dump file is stored under a different named graph.
We are collecting the query logs, and will share the most frequent
queries.
Cheers!
[1]
http://wikisparql.org/
[2]
http://spaziodati.eu/en/
[3]
http://tools.wmflabs.org/wikidata-exports/rdf/exports/20150223/
On 3/21/15 1:00 PM, wikidata-l-request(a)lists.wikimedia.org wrote:
On 3/20/15 2:08 PM, Markus Kroetzsch wrote:
>Dear all,
>
>Thanks to the people at the Center of Semantic Web Research in Chile
>[1], we have a very first public SPARQL endpoint for Wikidata running.
>This is very preliminary, so do not rely on it in applications and
>expect things to fail, but you may still enjoy some things.
>
>http://milenio.dcc.uchile.cl/sparql
You have a SPARQL that provides access to
Wikidata dumps loaded into an
RDF compliant RDBMS (in this case a Virtuoso RDBMS instance). I emphasis
"a" because "the first" isn't accurate.
There are other endpoints that provide access to Wikidata dumps:
[
1]http://lod.openlinksw.com/sparql -- 61 Billion+ RDF triples culled
from across the LOD Cloud (if you lookup Wikidata URIs that are objects
of owl:sameAs relations you'll end up in Wikidata own Linked Data Space)
[
2]http://wikidata.metaphacts.com/sparql -- another endpoint I
discovered yesterday .
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