Does it work when Subject is defined as *?

Like if you have a relation on Sergey's page defined as:

    Sergey knows [[Has friend::John Doe]] and [[Has friend::Jane Doe]] from high school and [[Has friend::Peter Smith]] from college.

and on Yaron's page defined as:

    Yaron knows [[Has friend::John Doe]] from college and [[Has friend::Peter Smith]] from work.

Regular query

    [[Has friend::*]]

will return:

   Sergey           John Doe
                        Jane Doe
                        Peter Smith

   Yaron             John Doe
                        Peter Smith

But what if I want to get result of "Is a friend of" (opposite to "Has friend") and expect results like this:

   John Doe        Sergey
                         Yaron

   Jane Doe        Sergey

   Peter Smith     Yaron
                         Sergey

What kind of query should I run? [[*::Has friend]] doesn't seem to help ;(


On 5/18/07, Yaron Koren <yaron57@gmail.com> wrote:
Well, my mistake - I tried it out, and it appears "inverse queries",
i.e. queries that return the object of triples, given the subject,
work. And it looks like the functionality has been in SMW for a
while... for some reason, it's not mentioned in the help page
(http://ontoworld.org/wiki/Help:Inline_queries), and I couldn't see
documentation anywhere else either. Is this a secret or unsupported
feature? In any case, good to know.

-Yaron


On 5/17/07, Yaron Koren <yaron57@gmail.com> wrote:
> This question is a little confusing to think about (at least for me),
> because "friend of" is, in real life, always a bi-directional
> relationship. So let me substitute something that's more clearly
> one-directional for this example: how about "has been to the house
> of".
>
> Looking at it that way, I don't believe your first example will work.
> I don't think there's any way to determine whom a person "has been to
> the house of" - you can only find out who "has been to the house of" a
> certain person. I think what you're looking for is an inverse query,
> which isn't supported, though the issue has come up before on this
> mailing list.
>
> -Yaron
>
>
> On 5/17/07, Jim Wilson <wilson.jim.r@gmail.com > wrote:
> > Hi SMW Devs,
> >
> > Quick question: is there a way to get a list of all articles that meet a
> > reflexive criteria?
> >
> > For example, I've got a relation called "friend of", and I know how to do
> > these types of queries:
> >
> > <ask>[[User:Whoever]][[friend of::*]]</ask> - This will return all articles
> > that User:Whoever is a "friend of"
> >
> > <ask>[[friend of::User:Whoever]]</ask> - This will return all articles that
> > are "friends of" User:Whoever
> >
> > Is there a way to get the intersection of these two sets?  Meaning, everyone
> > who is both "friend of" User:Whoever, and who User:Whoever says they're
> > "friend of"?
> >
> > Thanks in advance for your help - I really appreciate it.
> >
> > And if the answer is "no, there's no pure SMW way to do that", that's fine
> > too - I can find another solution.  I just don't want to waste my time
> > looking for one if SMW can get the job done on its own.
> >
> > Thanks!
> >
> > -- Jim R. Wilson (jimbojw)
> >
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