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Re: Using bnode identifiers for predicates, graph names

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 06 Feb 2013 20:02:17 +0000
Message-ID: <5112B6C9.30900@epimorphics.com>
To: public-rdf-wg@w3.org


On 06/02/13 02:27, Manu Sporny wrote:
> On 02/05/2013 05:27 PM, Pat Hayes wrote:
>>>>>
>>>>> Could we introduce the concept of a 'blank graph identifier'?
>>>>
>>>> Sure - (1) create your own URI scheme or (2) a systematic way to
>>>>   generate UUIDs based on doc and position of the graph in the
>>>> doc
>>>
>>> If we do #1 or #2, we're basically going to re-invent blank node
>>> identifiers.
>>
>> No, if you do #1, you will be using IRIs, which is in conformance
>> with (the letter of the) specs. So why not just do that? Its not hard
>> to do: just use a short alphanumeric string instead of "_" before the
>> colon.
>
> Okay, in this case, we are going to use "_g:". Would that be okay?
>
>> Why are you making so much fuss about it?
>
> _g: is effectively a blank-node-like identifier. We could generalize
> this and merge blank graph identifiers and blank node identifiers into a
> unified concept called the "dataset-local identifier". I think that
> would be a cleaner design than the "_g:" hack.
>
> More importantly, "_g:" is not just going to be the solution we use for
> the Web Payments / PaySwarm work, but it will be a part of another W3C
> specification called "RDF Dataset Normalization", which explains how to
> normalize an RDF Dataset, assigning blank graph identifiers to graphs
> that were not provided a name by their producers. So, this decision will
> bleed from JSON-LD, into RDF Dataset Normalization.

(recording a discussion point in the telecon)

If you want an identifier that is not written as a full URI, can be used 
with the file to refer to other things in the file, then one such 
mechanism is fragment identifiers.  This works in Trig as well.

"#graph1"

A fragment identifier does mean there is a absolute URI - it would be 
the base URI of the document, then #graph1.

They are "blank-node-like identifier" is the sense that are scoped to 
the document.

	Andy
Received on Wednesday, 6 February 2013 20:02:51 GMT

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