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/ent... 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/ent.... 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
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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@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.
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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