Yes, in the pizza example Emw showed, the definition of "food" is important. If what I ate this morning is a food, then pizza is a subclass of food. This is consistent with the first sentence of https://fr.wikipedia.org/wiki/Nourriture of frwiki. And the fact that "pizza" is an instance of food is a mistake, unfortunately a pretty common one on Wikidata. We should write a query to find all such examples where an item is both an instance and a subclass of the same class.

Now pizza is clearly a type of meal it could be relevant in a food classification and could be very well be an instance of it, as it's a preparation common people used to put whatever they can put on it, similarly to https://www.wikidata.org/wiki/Q12486

2015-10-18 18:31 GMT+02:00 Thad Guidry <thadguidry@gmail.com>:

The main problem is that Instance Of is not being used properly sometimes. In general, wrong classifications across Wikidata lead to weird assumptions.

Better documentation, and even helper rules to help prevent wrong classifications is what is needed and its forthcoming.

Lydia has mentioned that these kinds of problems will eventually become less and less as the Roadmap features eventually land into production.

I am looking forward to next year, and the year after, to see the quality improve.

Thad

+ThadGuidry

_______________________________________________
Wikidata mailing list
Wikidata@lists.wikimedia.org
https://lists.wikimedia.org/mailman/listinfo/wikidata