[[located in::Tokyo::Japan::Asia]] is actually a bad example of data model since this is more likely the case for transitive relationships when you only need to specify [[located in::Tokyo]] on object's case and [[located in::Japan]] on Tokyo page and [[located in::Asia]] on Japan page. Plus you need to indicate that "Property:located in" is a transitive property.

So it might be better to specify business case more clearly to get a good solution.

        Sergey


On Tue, Jun 24, 2008 at 9:45 AM, Markus Krötzsch <markus@semantic-mediawiki.org> wrote:
On Mittwoch, 18. Juni 2008, S Page wrote:
> Marc Feickert wrote:
> >  > Yes, amazingly and undocumentedly,
> >  > [[composer of::musician of::performer of::jazz]]
> >  > works. I think the help used to document this weird chaining, but it's
> >  > gone from http://ontoworld.org/wiki/Help:Annotation
> >  > That style would confuse a lot of human editors.
> >
> > So could this work in some fashion in the reverse? Here we have an
> > example of three properties pointing to the same individual. Can a
> > shorthand be used to point one property to three individuals? somethign
> > kind of like:
> > [[located in::Tokyo::Japan::Asia]]
> > If this were possible, it would in a sense resolve the
> > heirarchy/inference problem. It would not be automatic throughout the
> > system, still manual.
> >
> > Can such a thing be done?
>
> It could but the risk is existing pages that rely on chaining multiple
> properties to one value would break.

Yes. I really suggest to not use the name "chaining" here. A "chain"is
something where one cares about the order of the parts. But semantically the
following three are the same:

[[composer of::jazz]] [[musician of::jazz]] [[performer of::jazz]]

[[composer of::musician of::performer of::jazz]]

[[musician of::composer of::performer of::jazz]]

The "::" just separates many property names used on the same value. This is
so, since one would otherwise have to repeat a value on a page to use more
than one property for it. The availability of subproperties does of course
make many uses of this obsolete. In the above example, one could state
that "musician of" is a subproperty of "performer of" and only use the more
specific one (i.e. musician of) in annotations. But you see that this already
fails with composer and musician, which are really two different
relationships.

The "property1::property2::...::value" syntax is in fact very old, basically
something that SMW had for almost all of its life. So it can safely be
considered "stable" even if one might rather avoid it if not really needed
(we often use it in templates though). If you need a name for it, then you
could call it "property conjunction" since it states that property1 AND
property2 AND ... all have the same value.

There is no plan to make "chains" with pages in them available; this would
really be a completely different way of interpreting this syntax. Note that
we already have (in SVN) a syntax for real property *chains* in #ask queries:

{{#ask: [[located in.population::1000]] }}

looks for everything located in a place with a population of 1000. We consider
making property chains available for knowledge modelling, and this syntax
could then reappear there.

-- Markus

>
> Parsing is quirky and hard enough as it is; I think pages should make
> explicit simple annotations.  You could create a simple
> [[Template:Located in Tokyo]] that makes all three annotations.
>
> You could try to create a query that generates wiki text with semantic
> annotation, see http://semantic-mediawiki.org/wiki/Germany and
> http://semantic-mediawiki.org/wiki/California   Maybe someone could make
> a general [[Template:Generate-transitive-annotations]].
>
> As I said earlier in the thread, the alternative is to beef up your
> queries for Located_in.
>
> A radically different approach for location would be to write code for
> http://sandbox.semantic-mediawiki.org/wiki/Type:Box and support queries
> for geographical containment and intersection.
>
> --
> =S Page
>
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Semantic MediaWiki    http://semantic-mediawiki.org
http://korrekt.org    markus@semantic-mediawiki.org

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