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Re: Why do we name nodes and not edges?

From: Michael F Uschold <uschold@gmail.com>
Date: Fri, 27 Jul 2012 09:25:11 -0700
Message-ID: <CADfiEMP7PGzXquiVb5+RBrM0fAkGS0b1zkQNr3j6==B-anLpTg@mail.gmail.com>
To: Hugh Glaser <hg@ecs.soton.ac.uk>
Cc: Steve Harris <steve.harris@garlik.com>, Austin William Wright <aaa@bzfx.net>, Melvin Carvalho <melvincarvalho@gmail.com>, Semantic Web <semantic-web@w3.org>
Sure, reification is a bit of a pain sometimes if you have lots of nary
relations in your application domain.

But who is is a problem for? So it makes specifying raw queries a bit more
painful - agreed.  However end users need not know or care about it.  It
can be buried behind query interfaces and other things for end users.

Michael

On Fri, Jul 27, 2012 at 4:47 AM, Hugh Glaser <hg@ecs.soton.ac.uk> wrote:

>
> On 27 Jul 2012, at 09:37, Steve Harris <steve.harris@garlik.com> wrote:
>
> > Yeah, but that example uses reification, which is at best frowned upon.
> >
> > Increasingly my reaction to these kinds of questions is: maybe you
> shouldn't be using RDF.
> >
> > RDF has limits of expressivity, [all IMHO] it's best for describing
> things in a way that the descriptions can easily be consumed by other
> reasonably generic processors - once you start delving off into obscure
> corners - e.g. something that was said by person X, believed by person Y,
> but not person Z, and then published by W - then you're no longer in the
> territory of easily. Even once you've somehow parsed that lot, doing
> anything useful with it - in an even vaguely generic way - is beyond
> complex.
> I like this description.
> I like using SemWeb technologies for the things that they are good at,
> which in my brain means it has to be easy.
> People are welcome to think hard about how to push back the frontiers of
> what they might achieve, of course - that is research.
> I think the platform that others have toiled over in the last decade has
> provided us with something that can be easily used with confidence.
> But if some area is getting complex, than maybe it isn't the right
> technology.
> Which of course means it could benefit from more toil, of course, such as
> provenance is doing.
> Me? Clearly I'm just a parasite for others' toil.
> >
> > - Steve
> >
> > On 2012-07-26, at 16:30, Austin William Wright wrote:
> >
> >> At least in RDF, resources (the node of the graph) are first class
> citizens.. You can describe edges as resources, you just need give the
> resource an identifier first:
> >>
> >> <triple1234>
> >>     a rdf:Statement ;
> >>     rdf:subject <foo> ;
> >>     rdf:predicate <http://example.com/edge/123456> ;
> >>     rdf:object 1 .
> >>
> >> Since edges/RDF statements with the same subject, predicate, and object
> must be the same edge, this identifies edges. Any rdf:Statement resources
> with the same values for subject, predicate, object, would be different
> URIs for the same resource.
> >>
> >> We don't see this more often because usually edges aren't resources "of
> significance", there's not much reason to describe specific facts.
> Generally, people make statements on entire graphs of RDF statements, the
> graph getting a URI. These don't usually get stored themselves as RDF
> statements for practical database reasons, but you could, as an RDF
> Collection of rdf:Statement resources.
> >>
> >> Austin Wright.
> >>
> >> On Wed, Jul 25, 2012 at 8:07 AM, Melvin Carvalho <
> melvincarvalho@gmail.com> wrote:
> >> Sorry if this topic has been covered before, but I have a question
> based on the axioms of the web, in particular:
> >>
> >> Axiom 0a: Universality 2    Any resource of significance should be
> given a URI.
> >>
> >> In this case we consider the web to be a directed graph (of nodes and
> edges), where a node corresponds to a resource but edge does not.
> >>
> >> We are encouraged to make nodes universal by giving them a URI.
> >>
> >> Why dont edges get the same treatment, ie encouragment to give it a
> (universal) name.  Is it even practical?
> >>
> >> I know there's such thing as reification but that seems to be unpopular
> (maybe before my time).
> >>
> >> I'm just curious as to whether this seems asymmetrical, that nodes are
> seemigly treated in one way, and edges in another?
> >>
> >
> > --
> > Steve Harris, CTO
> > Garlik, a part of Experian
> > +44 7854 417 874  http://www.garlik.com/
> > Registered in England and Wales 653331 VAT # 887 1335 93
> > Registered office: Landmark House, Experian Way, Nottingham, Notts, NG80
> 1ZZ
> >
>
>
>


-- 

Michael Uschold, PhD
   Senior Ontology Consultant, Semantic Arts
   http://www.semanticarts.com
   LinkedIn: http://tr.im/limfu
   Skype, Twitter: UscholdM
Received on Friday, 27 July 2012 16:25:42 UTC

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