- From: Wolfgang Nejdl <nejdl@kbs.uni-hannover.de>
- Date: Tue, 25 Jun 2002 22:52:03 +0200
- To: Graham Klyne <GK@ninebynine.org>
- cc: Danny Ayers <danny666@virgilio.it>, pat hayes <phayes@ai.uwf.edu>, www-rdf-logic@w3.org
>
> At 07:28 PM 6/25/02 +0200, Danny Ayers wrote:
>
>
> > >WHY is this perceived as a problem? What use is there in referring
> > >to edges?
> >
> >hmm...
> >
> >[the cat] --[sat on]--> [the mat]
> > |
> > [for]
> > |
> > V
> > [an hour]
> >
> >could currently be broken down something like :
> >
> >[sat on] --[subclass]--> [sat on for an hour]
> >
> >[the cat] --[sat on for an hour]--> [the mat]
> >
> >[sat on for an hour] --[cardinality]--> [1]
> >
> >but it seems less clunky to say :
> >
> >[sat on for an hour] --[instanceOf]--> [sat on]
> >
> >[the cat] --[sat on for an hour]--> [the mat]
>
> Then if I say:
>
> [the dog] --[sat on for an hour]--> [the cat]
>
> this is clearly another instance of [sat on for an hour]. I.e. we're back
> to where we started.
>
No. You would have
[the dog] --[sat on]--> [the cat]
|
[for]
|
V
[an hour]
Referencing an arc (actually, a triple) by a specific ID, by the way,
is useful exactly in these cases, where relationships have additional
attributes. Another example would be
[John] -- [married] -- [Mary]
|
[date of marriage]
|
V
[July 4th, 1999]
or
[table] -- [connected to] -- [leg]
|
[kind of connection]
|
V
[nail]
This is done in several formalisms (such as O-Telos - we did some work
on a dialect we called O-Telos-RDF) and also in semantical data models
such as entity relationship diagrams. It is also useful for
reification in general, because you can say something about a
statement by referring to its statement ID.
Wolfgang
> #g
>
>
> -------------------
> Graham Klyne
> <GK@NineByNine.org>
Received on Tuesday, 25 June 2002 16:53:02 UTC