On 07.01.2017 15:27, Gerard Meijssen wrote:
Hoi, The biggest casualty of the current mess is that people like me do not care at all about it. It cannot be explained, nobody is interested in explaining it and consequently there is little use for it. It is "must have" so it is there.. fine, lets move on.
The subclass of and instance of statements are actually used in very many WDQS queries, often with * expressions to navigate the hierarchy. WDQ also had a special feature TREE for this purpose. So I'd say that this part of the data is rather important to Wikidata. But if you find little use in it, that's ok too. Nevertheless, we should try to fix the modelling errors there, since they will affect many other people's Wikidata experience.
Cheers, Markus
On 7 January 2017 at 10:39, Markus Kroetzsch <markus.kroetz...@tu-dresden.de <mailto:markus.kroetz...@tu-dresden.de>> wrote: On 06.01.2017 18:24, Thomas Douillard wrote: Same entity can be treated both as class and individual This is valid for OWL as well. Yes, and since Wikidata does not feature very powerful ontological statements, you could treat this like in OWL 2 DL semantically as well, i.e., a weak approach where the "class" and the "instance" are not really identified works. Nevertheless, using the ontology might still be challenging depending on what you want to do with it, since there are quite a few meta-levels (classes of classes of classes ...) that are not cleanly separated. When I last checked, we even had some instance-of cycles ;-) Even this is not a technical problem for the OWL semantics, but maybe for some tools and approaches. Cheers, Markus 2017-01-05 22:21 GMT+01:00 Stas Malyshev <smalys...@wikimedia.org <mailto:smalys...@wikimedia.org> <mailto:smalys...@wikimedia.org <mailto:smalys...@wikimedia.org>>>: 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 <https://github.com/Wikidata/Wikidata-Toolkit> <https://github.com/Wikidata/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_download.html <http://tools.wmflabs.org/wikidata-exports/rdf/exports/20160801/dump_download.html> <http://tools.wmflabs.org/wikidata-exports/rdf/exports/20160801/dump_download.html <http://tools.wmflabs.org/wikidata-exports/rdf/exports/20160801/dump_download.html>> 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 smalys...@wikimedia.org <mailto:smalys...@wikimedia.org> <mailto:smalys...@wikimedia.org <mailto:smalys...@wikimedia.org>> _______________________________________________ Wikidata mailing list Wikidata@lists.wikimedia.org <mailto:Wikidata@lists.wikimedia.org> <mailto:Wikidata@lists.wikimedia.org <mailto:Wikidata@lists.wikimedia.org>> https://lists.wikimedia.org/mailman/listinfo/wikidata <https://lists.wikimedia.org/mailman/listinfo/wikidata> <https://lists.wikimedia.org/mailman/listinfo/wikidata <https://lists.wikimedia.org/mailman/listinfo/wikidata>> _______________________________________________ Wikidata mailing list Wikidata@lists.wikimedia.org <mailto:Wikidata@lists.wikimedia.org> https://lists.wikimedia.org/mailman/listinfo/wikidata <https://lists.wikimedia.org/mailman/listinfo/wikidata> _______________________________________________ Wikidata mailing list Wikidata@lists.wikimedia.org <mailto:Wikidata@lists.wikimedia.org> https://lists.wikimedia.org/mailman/listinfo/wikidata <https://lists.wikimedia.org/mailman/listinfo/wikidata> _______________________________________________ Wikidata mailing list Wikidata@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikidata
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