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Re: Labelled graphs

From: Steve Harris <steve.harris@garlik.com>
Date: Mon, 16 Apr 2012 13:13:50 +0100
Cc: public-rdf-wg@w3.org
Message-Id: <D6E38A2C-BFE2-4FB0-BBFA-CA09221A4B76@garlik.com>
To: Andy Seaborne <andy.seaborne@epimorphics.com>
On 2012-04-16, at 13:07, Andy Seaborne wrote:
> 
> On 15/04/12 15:57, Sandro Hawke wrote:
>> On Sat, 2012-04-14 at 20:35 +0100, Andy Seaborne wrote:
>>> On 13/04/12 11:33, Steve Harris wrote:
>>>>> Read that as rdf:aaa to avoid natural language meaning.
>>>> I don't get that, butů
>>> 
>>> Natural language can be confusing.
>>> 
>>> <u>  rdf:label G .
>>> 
>>> so is<u>  labelled by G ?
>>>     "<u>  has a label of G"
>>>     "G is a label for<u>"
>>> 
>>> or is<u>  labelling G ?
>>>     "<u>  is a label for G"
>>>     "G has a label of<u>"
>>> 
>>> (sometimes it does not matter -- e.g. sameValue).
>>> 
>>> "labelled graphs" is more of the style"<u>  is a label of G".
>>> 
>>> All that is needed as the most basic building block is a neutral
>>> association of (<u>, G) and that within a dataset (<ui>, Gi) is
>>> functional from<ui>  to Gi : given a label, find the associated graph.
>> 
>> With these looser semantics, I don't think it needs to be functional.
>> Rather, I think we can define it as labeling the associated graph and
>> each of its subgraphs.
>> 
>> There would be some kind of deep equivalence between these two datasets:
>> 
>> D1:
>>    <u>  {<a>  <b>  1 }
>>    <u>  {<a>  <b>  2 }
>> and
>> D2:
>>    <u>  {<a>  <b>  1,2 }
>> 
>> The SPARQL semantics might written in terms of a normal form, where a
>> term is only used as a label once, but the other forms would be valid in
>> trig and in the RDF Semantics.
> 
> In earlier threads, the proposal was that a TriG document had one graph per label but (syntax) it may be split into separate sections for practical reasons.

That matches my intuition about what 

> <u>  {<a>  <b>  1 }
> <u>  {<a>  <b>  2 }

Is trying to express.

- Steve

-- 
Steve Harris, CTO
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Received on Monday, 16 April 2012 12:14:27 UTC

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