I think it's important to consider the distinction between a category system and semantic queries. I think it's very likely that DBpedia and Wikidata will converge over time and develop a simple enough query interface that causes fewer people to use the category system because we will be able to automatically generate relevant queries related to a given article. DBpedia currently has a lot more data, but Wikidata is important for many editing scenarios. Also, in the future I think there will be a lot of content scenarios where it is natural to start by putting data into Wikidata and then including it in articles instead of just extracting information from articles. If you are familiar with query languages you can get comfortable with the DBpedia SPARQL examples in a few minutes, but for a typical reader that just wants to go from an article about a person to a list of similar people it is hard to beat scrolling down and just clicking on a category. I did a test query on DBpedia to plot all sports cars by their engine sizes, and I think for the types of things it enables you to do it is totally worth the learning curve. That being said, I think the category system has a lot of potential for better browsing scenarios as opposed to queries. I've been making a tool that mixes the article view data with the category system. You can see a video of the basic idea here and a screenshot of football league popularity split by language.
I'm currently multiplying the Chinese traffic by 30 to try and account for Baidu Baike.
> Date: Sat, 4 May 2013 08:14:54 +0200
> From: jane023@gmail.com
> To: wikidata-l@lists.wikimedia.org
> Subject: Re: [Wikidata-l] Question about wikipedia categories.
>
> Wondering exactly the same thing - my frustrations with categories
> began about three years ago and it seems I am surprised monthly by
> severe limitations to this outdated apparatus. I am a heavy category
> user, but I would love to be able to kick it out the door in favour of
> a more structured method. As far as I can tell, there is very little
> synchronisation among language Wikipedias of category trees, and being
> able to apply a central structure to all Wikipedias through Wikidata
> sounds like a great idea, and one which would not disturb the current
> category trees we already have, but supplement them. As I see it, some
> category structures are OK, but when categories get big, people split
> them in non-standard ways, causing problems like this recent
> media-hype regarding female novellists. I think that it's great this
> is in the news in this way, because I am sure that most Wikipedia
> readers never knew we had categories, and this is a great introduction
> to them, as well as an invitation to edit Wikipedia.
>
> 2013/5/4, Chris Maloney <voldrani@gmail.com>:
> > I am just curious if there has ever been discussion about the
> > potential for reimplementing / replacing the category system in
> > Wikipedia with semantic tagging in WikiData. It seem to me that the
> > recent kerfuffle with regards to "American women writers" would not
> > have happened if the pages were tagged with simple RDF assertions
> > instead of these convoluted categories. I know, of course, that it
> > would be a huge undertaking, but I just don't see how the category
> > system can continue to scale (I'm amazed it has scaled as well as it
> > has already, of course).
> >
> > I am trying to learn more about wikidata, and have perused the various
> > infos and FAQs for the last two hours, and can't find any discussion
> > of this particular issue.
> >
> > -- Chris
> >
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