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Re: RDF-ISSUE-107 (blank-node-definition): Definition of blank nodes (editorial-ish) [RDF Concepts]

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 07 Nov 2012 21:43:14 +0000
Message-ID: <509AD5F2.2090008@epimorphics.com>
To: public-rdf-wg@w3.org


On 07/11/12 17:06, RDF Working Group Issue Tracker wrote:
> RDF-ISSUE-107 (blank-node-definition): Definition of blank nodes
> (editorial-ish) [RDF Concepts]
>
> http://www.w3.org/2011/rdf-wg/track/issues/107
>
> Raised by: Richard Cyganiak On product: RDF Concepts
>
> Pat commented on the definition of blank nodes in Concepts section
> 3.4.
> http://lists.w3.org/Archives/Public/public-rdf-wg/2012May/0654.html
>
>
> "The blank nodes in an RDF graph are drawn from an infinite set."

Minor: If wanted, I think this can be used with modification:

"The blank nodes in an RDF graph are drawn from some arbitrary infinite 
set, which is disjoint from the set of IRIs and set of all literals."

>
> This seems a rather odd way to introduce the idea. I know it is
> formally correct, but it reads (to me) rather jarringly. (Which set?
> Why that set in particular? Etc..)
>
> Suggest something more like:
>
> "A blank node is a node which has no associated information or
> structure. In an RDF graph, a blank node represents an 'unknown'
> entity which may not have a name. In the abstract syntax, we specify
> only that blank nodes are taken from a fixed infinite set which is
> disjoint from the set of all IRIs and the set of all literals."

I think that "no associated information or "structure" is confusing - it 
has properties and participates in triples.

It is not "an entity" - that sounds more like bNodes as anonymous 
individuals which they are not.  As a node in the graph it does not have 
a name (it's blank!).  (It can be an existential for resources that has 
one or more names but it itself is still blank.)

"A blank node is a node in an RDF graph that does not have an IRI nor is 
it a literal."


> "Given two blank nodes, it is possible to determine whether or not
> they are the same."

Works for me - c.f.

"Given two integers, it is possible to determine whether or not
they are the same." A bit loose maybe but comprehensible.

There are two graph nodes from two sources (e.g. two triples).  Are they 
the same (you have pointers to them, not the things themselves).

>
> Um. I know I am always being acussed of thinking like a
> mathematician, but this doesn't make sense as stated. If there are
> TWO blank nodes, then obviously they aren't the same, because if they
> were there would only be one of them. I know it is hard to say this
> without using words like "identity", so I suggest simply omitting
> this sentence altogether, and rephrase the paragraph as something
> like
>
> "RDF makes no reference to any internal structure or syntactic form
> of blank nodes. A blank node is simply a node in an RDF graph which
> has no label or other structure relevant to its RDF role."
>
>
>
>
Received on Wednesday, 7 November 2012 21:43:49 GMT

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