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Re: Dataset semantics

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Wed, 19 Oct 2011 14:32:52 +0100
Message-ID: <4E9ED184.3040406@epimorphics.com>
To: public-rdf-wg@w3.org

On 18/10/11 16:25, Antoine Zimmermann wrote:
> Dear all,
> I was overloaded with other things and haven't participated in the
> recent discussions around graph and dataset semantics but I am now
> catching up and these are some thoughts I have after reading all that
> was said. I'd like to get your opinion on this.
> These are some things I expect regarding the semantics of datasets:
> 1. They should not impact the semantics of RDF;
> 2. There is no single fit-for-all semantics of datasets so the semantics
> must be flexible to accomodate use cases and existing implementations;
> 3. There should exist a way to tell the world what specific semantics
> one application is using.
> Item 1 implies that the semantics of datasets are distinct from the
> semantics of RDF.
> Item 2 implies that different conformant applications may entail
> different things. Yet, there should be common requirements to make a
> semantics "conformant".
> Item 3 is rather open but I am thinking of something like a description
> of a dataset that says, e.g., "bnodes are locally scoped" or (following
> Sandro's proposal) "graph labels are used to RDF-denote the graph
> containers" or "the default graph is the union of the named graphs" or
> "the default graph represents shared knowledge, valid in all named
> graphs", etc... All these statements say something about the semantics
> of datasets that is used in a system.
> Regarding the minimal requirements for a semantics of datasets, there is
> already a proposal [1]. I updated it to make it clearer. That proposal
> addresses many of the issues that Richard puts forward in a recent email
> [2]. In particular, it says that what is "true in a graph" (or, in a
> context) is not necessarily true in a different graph (or context). This
> minimal semantics does not provide any means of talking about an RDF
> Graph. This should be addressed by the mechanism that I envision in Item
> 3 above.
> [1] Semantics (in TF-Graphs/RDF-Datasets-Proposal).
> http://www.w3.org/2011/rdf-wg/wiki/TF-Graphs/RDF-Datasets-Proposal#Semantics

[1] seems reasonable to me.


> [2] Datasets and contextual/temporal semantics.
> http://lists.w3.org/Archives/Public/public-rdf-wg/2011Oct/0212.html
Received on Wednesday, 19 October 2011 13:33:24 UTC

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