Hi!
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.
Also, Wikidata Toolkit (
https://github.com/Wikidata/Wikidata-Toolkit)
can be used to generate something like taxonomy - see e.g.
http://tools.wmflabs.org/wikidata-exports/rdf/exports/20160801/dump_downloa…
But one has to be careful with it as Wikidata may not (and frequently
does not) follow assumptions that are true for proper OWL models - there
are no limits on what can be considered a class, a subclass, an
instance, etc. Same entity can be treated both as class and individual,
and there may be some weird structures, including even outright errors
such as cycles in subclass graph, etc. And, of course, it changes all
the time :)
--
Stas Malyshev
smalyshev(a)wikimedia.org