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Re: Why do we name nodes and not edges?

From: Austin William Wright <aaa@bzfx.net>
Date: Thu, 26 Jul 2012 08:30:34 -0700
Message-ID: <CANkuk-Un7_inzoy1Z=xMCSm6MX0aA1z1rxGhM+f793dDkq0Cwg@mail.gmail.com>
To: Melvin Carvalho <melvincarvalho@gmail.com>
Cc: Semantic Web <semantic-web@w3.org>
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:

    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

> 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?
Received on Thursday, 26 July 2012 15:31:58 UTC

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