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Re: Issues danc-01 Re: 2 formalities in RDF concepts

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Tue, 28 Jan 2003 18:22:53 +0100
To: www-rdf-comments@w3.org, connolly@w3.org
Message-Id: <200301281822.53733.jjc@hpl.hp.com>


Hi Dan,

before the WG discusses this issue I wanted to understand your concern.

I believe that you think the concept described in

6.3 Graph Equality
http://www.w3.org/TR/rdf-concepts/#section-graph-equality

is one that is relevant to RDF and should be described in RDF Concepts, but 
that you take issue with it being labelled "Equality". Earlier drafts called 
this concept "Isomorphism"

see:
3.6 Graph Equality
http://www.w3.org/TR/2002/WD-rdf-concepts-20020829/#xtocid103648
(which uses both terms)


If I have two N-triple files of one line each

<eg:a> <eg:b> _:x .

and

<eg:a> <eg:b> _:y .

Do you think they are equal or unequal?

Personally, I would say they are equal as RDF graphs, and unequal as text 
documents.

Another example about the usage of the word equal, from mathematics, would be:
  Take a piece of paper. Near the top draw a circle and put three blobs on it.
  Near the bottom draw a triangle with a blob on each corner.
  It would be normal practice in graph theory to say that:
 Both the circle and the triangle form plane graphs (with the blobs as nodes).
 And that the two graphs are equal (as graphs).
 While from a different point of view they are clearly unequal.

I'm trying to understand what your issue is, I guess I need to hear a bit more 
from you.

Jeremy
Received on Tuesday, 28 January 2003 12:22:01 GMT

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