Yaron Koren wrote: > > Conversely, the relationship between an article on Urban Planning and > > a City category is _not_ an "is-a" relationship: Urban Planning is not > > a city. But while it's not a valid class/instance relationship, it > > _is_ a valid category/article relationship. > > Well, "valid" is in the eye of the beholder. :) It's valid in Wikipedia, but > on other wikis (like mine), it could be considered invalid: technically > possible, but incorrect.
...and your solution is to try to change this so that it's invalid for everyone, whether they like it or not. Let's take a look at two possible outcomes: if I get my way, you are still free to insist that people use Categories exclusively for class/instance relations on SMWs that you run, and I am free to permit people to use other kinds of category/article relations on SMWs that I run. If you get your way, you will still be able to handle your semantic wikis the way that you want to; but I will be forced to manage my semantic wikis the way that you think they ought to be managed. The only way that insisting on requiring everyone to use your approach makes any sense is if there are technical difficulties that render the alternative impractical. So far, you have not shown anything of the sort. The best you've managed has been to show that your approach works - which I have never disputed, BTW. _________________ So: what technical difficulties are there with the alternatives? For clarity, I'll summarize what I consider to be the most appropriate alternative: [*] Add a special property called Class that works exactly like Category annotations currently work. That is: it establishes a class/instance relationship (e.g. rdf:type) between a category and an article, or a class/subclass relationship (e.g. rdfs:subClassOf) between two categories, both conceptually and semantically. [*] Change the implementation of the Category annotation so that it no longer promises anything other than that there is some sort of transitive relationship between the article or category that it's in and the category that it refers to. _________________ I see one technical difficulty with this, and one other practical difficulty. If you see any others, please let me know. The technical difficulty comes when exporting to OWL/RDF: since you don't represent the generic category/article relationship using rdf:type and you don't represent the generic category/subcategory relationship using rdfs:subClassOf, how _do_ you represent them? Or do you? This difficulty can be resolved by noting that the traditional relationships used for wiki categorization aren't semantic, any more than standard page references are. As far as I can tell, non-Property page references don't get exported to OWL/RDF; so one solution to this dilemma would simply be to not export categorization done by means of '[[Category:xyz]]'. In short, if you want _anything_ on a SMW page to have semantic meaning, use a Property to annotate it. Anything. Including "is-a". Conversely, if you don't use a Property to annotate something, it doesn't carry any semantic value. _________________ The practical difficulty is that there are already SMWs up and running that are using categories as classes. Making this change would require them to replace all existing '[[Category:xyz]]' markup with '[[Class::xyz]]' property annotations in order to maintain exactly the same behavior they currently exhibit. This can be done by bot, but still represents significant effort for little apparent gain. And the longer it takes to implement this change, the more insurmountable this practical difficulty becomes. The only solution that I can see to this dilemma is to implement the change as an extension. The result will be two basic kinds of SMWs: those that use standard Category markup to carry semantics, and those that handle all of their semantics by means of Property annotations. These two varieties can then compete with each other in the general marketplace; if the latter proves popular enough that more new SMWs are using it than aren't, then it can be integrated into the core; if not, at least it's still available to those who want it. -- Jonathan "Dataweaver" Lang ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Semediawiki-devel mailing list Semediawiki-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/semediawiki-devel
