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Re: Graphs and Being and Time

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Tue, 01 Mar 2011 11:30:26 +0000
Message-ID: <4D6CD8D2.70807@epimorphics.com>
To: nathan@webr3.org
CC: RDF WG <public-rdf-wg@w3.org>


On 01/03/11 10:32, Nathan wrote:
> Hi David,
>
> Sorry, I've realised the below is wrong, so corrected:
>
> Nathan wrote:
>> David Wood wrote:
>>> On Feb 24, 2011, at 13:12, Pat Hayes wrote:
>>>
>>>> It is much simpler: it is just wanting the WG to acknowledge that
>>>> "an RDF graph" can either be a mathematical set, or it can be some
>>>> kind of document or data structure or file than can be transmitted
>>>> over a computer network. But it can't be both.
>>>
>>> What is the difference between an "RDF graph" and a RESTful
>>> "resource"? What is the difference between an "RDF graph token" and a
>>> RESTful "representation"?
>>
>> REST maps a resource to a set of values over time, each single value
>> has a 1:N relationship with representations, "RDF Graph" (the
>> mathematical set, platonic abstraction, g-snap) equates to a single
>> value, and "RDF Graph Token" equates to a representation of that
>> single value.
>
> REST maps a resource to a set of values over time, each single value is
> a representation, representation equates to "RDF Graph Token" (a chunk
> of rdf/xml or turtle, a g-text in Sandro's mail).

This confuses me - aren't the bytes (representation) seen a matter for 
content negotiation and that happens on access?

The value is not a representation, the encoding of the value is the 
representation.  A representation is the result of an HTTP GET (or etc) 
and is determined at the point of access and includes "Accept". That's 
what I read from AWWW 2.2

At any point in time, an information resource is a value, which is 
abstract (c.f. the value 10) - a document is abstract if it "consists of 
words and punctuation symbols and graphics and other artifacts that can 
be encoded". It becomes confusing because a document itself can be about 
something.

Let me try a mapping:

g-box - place holding a sequence-over-time of values
g-snap - one such value
g-text - the REST representation.


On 24/02/11 15:06, Antoine Zimmermann wrote:
 > I agree that this distinction has to be made clearer, but isn't a graph
 > supposed to be a mathematical object, something which is inherently
 > abstract? To me, "RDF abstract graph" sounds redundant.

+1

There are uses of "RDF graph" outside the RDF specs in all the material 
that has been written about RDF.  We ought to minimise the effects on 
that material.

	Andy
Received on Tuesday, 1 March 2011 11:31:06 UTC

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