On Fri, May 10, 2013 at 1:43 AM, Dmitriy Sintsov questpc@rambler.ru wrote:
On 09.05.2013 20:28, Brad Jorsch wrote:
On Wed, May 8, 2013 at 10:47 PM, James Forrester jforrester@wikimedia.org wrote:
- Pages are implicitly in the parent categories of their explicit
categories
- -> Pages in <Politicians from the Netherlands> are in <People from the
Netherlands by profession> (its first parent) and <People from the Netherlands> (its first parent's parent) and <Politicians> (its second parent) and <People> (its second parent's parent) and …
- -> Yes, this poses issues given the sometimes cyclic nature of
categories' hierarchies, but this is relatively trivial to code around
Category cycles are the least of it. The fact that the existing category hierarchy isn't based on any sensible-for-inference ontology is a bigger problem.
Let's consider what would happen to one of my favorite examples on enwiki:
- The article for Romania is in <Black Sea countries>. Ok.
- And that category is in <Black Sea>, so Romania is in that too.
Which is a little strange, but not too bad.
- And <Black Sea> is in <Seas of Russia> and <Landforms of Ukraine>.
Huh? Romania doesn't belong in either of those, despite that being equivalent to your example where pages in <Politicians from the Netherlands> also end up in <People> via <Politicians>.
There is probably nothing contradictionary in your Black sea category relation example because "Seas of <country>" implies that <country> has *multiple* seas, while Romania has only *one* sea border (no offence, there are lot of small countries and large country does not always means a happy life). <Landforms of Ukraine> is a little bit more weird, but could be explained as long and complex area of Crimean peninsula. So, the categories actually are not so wrong.
I think you misunderstood. The point was that the article on *Romania* would end up in <Seas of Russia> and <Landforms of Ukraine>.
OTOH, I missed the part of James's original proposal about creating the whole ontology using this inference system from scratch on Wikidata based on strict is-a relationships. So <Black Sea countries> wouldn't be in <Black Sea> in the Wikidata ontology, because countries aren't the sea.