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Re: Why do we name nodes and not edges?

From: Steve Harris <steve.harris@garlik.com>
Date: Wed, 25 Jul 2012 17:07:43 +0100
Cc: semantic-web@w3.org
Message-Id: <49968D34-E448-4DAB-A831-AC0F2F194391@garlik.com>
To: Aidan Hogan <aidan.hogan@deri.org>
Perhaps, but the distinction between a label for a property, that's unique to that edge, and the name of an edge is rather a subtle one.

If he was thinking of edge as in the combination of two nodes, and an edge label, then I would have though "triple" would be a better word, and there are numerous well-known solutions to that question.

- Steve

On 2012-07-25, at 16:47, Aidan Hogan wrote:

> Steve,
> 
> If I understand Melvin's point, in RDF, edge:123456 is the URI of a property used to label the edge, not the edge itself.
> 
> Analogously, you don't identify a class-instance by it's class URI.
> 
> An edge is between two things. It might be directed and it might be labelled. In RDF it's both.
> 
> Hence, the edge would encapsulate the full triple, including source (subject) and target (object) nodes, as well as the label (predicate).
> 
> Cheers,
> Aidan
> 
> On 25/07/2012 16:18, Steve Harris wrote:
>> Nothing stops you from giving edges a unique URI, infact I think I've
>> worked on systems that did that.
>> 
>> e.g.
>> 
>> <foo> <http://example.com/edge/123456> 1 .
>> <http://example.com/edge/123456> a rdf:Property .
>> ...
>> 
>> - Steve
>> 
>> On 2012-07-25, at 16:07, Melvin Carvalho 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
>> 
> 
> 

-- 
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
Received on Wednesday, 25 July 2012 16:08:17 UTC

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