Hi Rüdiger,
Daniel refers to several independent aspects of Wikidata:
(1) The ontology is not separated from the data. Schematic information
is mostly managed by encoding it in data as well. Therefore, if you want
some of it (but not the rest), then some extraction will be necessary.
The Wikidata SPARQL service is your friend for not-too-big (up to some
100K triples) on-the-fly data exports, enough to get the whole class
hierarchy, for example. We also have created some ontology-like excerpts
in the past [1]. These have been done offline by processing the data
dump using Wikidata Toolkit.
(2) The ontology is very lightweight. Wikidata mostly encodes properties
and their types, some hierarchical information on properties and
classes, and some "weak" hints on things like domain and range for some
properties. So there are no complex OWL axioms there. This is also the
reason why the ontology should not contain any logical contradictions --
when Daniel refers to "contradictions" I guess he means incoherences in
the overall modelling (which contradict human intuition).
(3) The ontology may change at any time. This is a consequence of (1)
and the fact that Wikidata is controlled by a global community.
For all of these reasons, there cannot be one "Wikidata ontology" but
there might still be many useful ontological things you can get without
too much effort.
If you are interested in learning about the classes and properties used
in Wikidata to get an informal idea of its current schema and content,
then you could also browse this data in SQID [2].
Best regards,
Markus
[1]
http://tools.wmflabs.org/wikidata-exports/rdf/exports/20160801/dump_download.html
[2] https://tools.wmflabs.org/sqid/#/browse?type=properties
On 05.01.2017 16:15, Daniel Kinzler wrote:
Am 04.01.2017 um 11:00 schrieb Léa Lacroix:
Hello,
You can find it here: http://wikiba.se/ontology-1.0.owl
If you have questions regarding the ontology, feel free to ask.
Please note that this is the *wikibase* ontology, which thefines the meta-model
for the information on Wikidata. It defines models statements, sitelinks, source
references, etc.
This ontology does not model "real world" concepts or properties like location
or color or children, etc. Modeling on this level is done on Wikidata itself,
there is no fixed RDF or OWL schema or ontology.
The best you can get in terms of "downloading the wikidata ontology" would be to
download all properties and all the items representing classes. We currently
don't have a separate dump for these. Also, do not expect this to be a concise
or consistent model that can be used for reasoning. You are bound to find
contradictions and lose ends.
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