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Re: Concepts (almost) ready

From: Richard Cyganiak <richard@cyganiak.de>
Date: Tue, 17 Dec 2013 19:29:03 +0000
Cc: Markus Lanthaler <markus.lanthaler@gmx.net>, RDF Working Group WG <public-rdf-wg@w3.org>, David Wood <david@3roundstones.com>
Message-Id: <CD547089-ED86-48FA-86CE-2A73220977C8@cyganiak.de>
To: Pat Hayes <phayes@ihmc.us>
Pat,

On 17 Dec 2013, at 18:35, Pat Hayes <phayes@ihmc.us> wrote:
>>> 4.  "Blank nodes MAY be shared between graphs in an RDF dataset."  Um, I now see that this can be understood in different ways. What I think (hope) is intended here is, that if the same bnodeID is used in two graph documents in the same dataset, then that means that those two graphs do share a bnode. But what it could be read as saying is that whether or not they share the bnode is optional: they might or they might not. Which would be a very unfortunate reading. 
>> 
>> You are right.
>> 
>> How about simply lowercasing the MAY? It's not meant as something that's optional for conformance, but simply to indicate a possibility. So, MAY in the RFC2119 sense is inappropriate.
> 
> agreed.
> 
>> Alternatively, “can be shared”.
> 
> All improvements, but they still don't rule out the unfortunate reading. I think extra words are needed to do that, unfortunately.

I’m worried about making this much more wordy, and would prefer not to talk about blank node identifiers there.

Technically speaking, the sentence is unnecessary anyway. In the absence of a statement that requires the blank nodes in distinct graphs to be disjoint, having shared blank nodes is allowed. Right? The sentence is just there to dispel a historic misconception. Drawing even more attention to that old misconception will only confuse future readers, I think.

So, after Markus’ latest edits this now reads:

[[
Blank nodes can be be shared between graphs in an RDF dataset.
]]

How about *removing* this sentence, and instead *adding* a new one to the informative note below:

[[
There is no requirement for the blank nodes in different graphs of an RDF dataset to be disjoint. For example, the same blank node could occur in a triple of the default graph and in a different triple of a named graph.
]]

Would that work for you?

Richard
Received on Tuesday, 17 December 2013 19:29:33 UTC

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