I think the issue is simply a problem of terminology right now.

Wikidata as it is does have no support for "Classes".

In the future, there will be Wikidata Queries.

A Wikidata Query is similar to a class description in OWL.

There is no need to create an item "Douglas Adams Novels". You can, though, have a Query "Douglas Adams Novels", and change its label, etc. Wikidata Queries will also have labels, an ID, etc.

Does this make sense?





On Thu Mar 06 2014 at 11:33:36 AM, Thomas Douillard <thomas.douillard@gmail.com> wrote:
Hi Lydia, in languages such as OWL, a class of item can be defined by a predicate on the properties and values of the item. Will we be able to link a class Qitem to a Wikidata complex query  in the corresponding namespace ? For example if we define a class "Douglas Adams Novels" whose instances are the members of the example query you gave ?



2014-03-06 19:24 GMT+01:00 Lydia Pintscher <lydia.pintscher@wikimedia.de>:

On Tue, Mar 4, 2014 at 9:01 PM, David Cuenca <dacuetu@gmail.com> wrote:
> I would like to make you aware of this RFC started by Gerard:
> https://www.wikidata.org/wiki/Wikidata:Requests_for_comment/Define_lists_on_both_%22Wikimedia_lists%22_and_%22Wikimedia_categories%22
>
> It is interesting because in the end, what is the difference between a list,
> a category, and a query? Not much, really.
>
> I'm curious to know if the approach taken with queries will be the same as
> the WDQ
> http://tools.wmflabs.org/reasonator/?&q=6573995
>
> Items like "List of..." or "Category:" would have some use, but the
> development notes don't state if this is the intended path
> https://meta.wikimedia.org/wiki/Wikidata/Development/Queries
>
> Any thoughts about it?

I've been trying to understand the RfC 3 times now and still fail. So
I can't answer your questions unfortunately.

The short and simplified version of how complex queries will work:
* someone defines a query on a page in a special query namespace (eg
"everything that has author = Douglas Adams")
* the result of the query is a list of items matching the query
* the Wikipedias can include the result of the query and visualize it
in certain ways on a page. (eg the wikitext of the article "List of
works by Douglas Adams" would have a call to include the query result
from Wikidata)


Cheers
Lydia

--
Lydia Pintscher - http://about.me/lydia.pintscher
Product Manager for Wikidata

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