Hi all,
We have a lot of statements saying that something is an instance of a
"Wikipedia disambiguation page" (Q4167410). Unfortunately, this kind of
information says something about a particular Wikipedia article in a
particular language, and often is not true for other languages.
Moreover, even if there is a language where the according article is
marked as disambiguation page, it is still common that the page gives a
description of a real item.
Example (bad use of instance of:Wikipedia disambiguation page)
==============================================================
https://www.wikidata.org/wiki/Q247819 (VW Polo)
Enwiki (like many languages) has a normal article here that is not a
disambiguation page. It says "The Volkswagen Polo is a supermini car
produced by the German manufacturer Volkswagen". That's very different
from "The Volkswagen Polo is a disambiguation page."
Even Wikipedias where the VW-Polo article is marked as disambiguation
page do not claim that the thing they are talking about is the
disambiguation page. For instance, frwiki has the article in
Catégorie:Homonymie, yet it says:
"Volkswagen Polo est une automobile, de la gamme des polyvalentes, de la
marque allemande Volkswagen"
Again, it is not said that VW Polo is a disambiguation page, even though
the page (not the car) is marked as one.
Proper use of instance of:Wikipedia disambiguation page
=======================================================
Now there are also many proper disambiguation pages. They do not have a
joint concept, other than the ambiguous title in a particular language.
Examples:
https://en.wikipedia.org/wiki/Jaguar_(disambiguation)
and, entertainingly:
https://en.wikipedia.org/wiki/Disambiguation_(disambiguation)
An item that is "instance of:Wikipedia disambiguation page":
* should not have sitelinks to pages that are not disambiguation pages
(an item can either be about a Wikipedia page or about a car, but these
should be kept separate),
* should always use the exact page title as the label (because this is
the real label of the page; the page "Jaguar (disambiguation)" is not
called "Jaguar" by anybody),
* should hardly have any statements at all, since there is almost
nothing that you can truthfully say about a group of pages in many
different languages, and since we want to avoid project-specific
statements (that's one reason we have badges as part of site links).
Whether disambiguation pages should have more than a single sitelink at
all is another question. In my view, if we are talking about a "page",
it is not the same page in French as it is in English (most properties
that pages could naturally have, such as authors, language, creation
date, etc. apply to a single page only). However, I can see that it is
practical to group such pages nonetheless.
Conclusion
==========
It would be nice if somebody could analyse this problem in more detail
(how many of our "disambiguation page" items have statements that are
obviously not about a page but about a car make, animal, etc.). We might
need some manual effort to clean this up (basically, a kind of
un-merging game).
The immediate conclusion is that we need to be much more careful
importing this type of information from one Wikipedia, since it is (by
its very nature) not project-independent and not universal across languages.
Cheers,
Markus