W3C home > Mailing lists > Public > public-rdf-wg@w3.org > October 2011

Re: Web Semantics for Datasets

From: Richard Cyganiak <richard@cyganiak.de>
Date: Fri, 7 Oct 2011 16:57:03 +0100
Cc: RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <C3372F9D-9714-40F6-8691-1F2FA73603E6@cyganiak.de>
To: Sandro Hawke <sandro@w3.org>
On 7 Oct 2011, at 15:07, Sandro Hawke wrote:
>> The way I see it, the proposal is backwards. We want to specify an abstract, idealised information space – a collection of RDF graphs. How to access that information space (dereferencing, SPARQL, N-Quads dumps, etc) is an implementation detail that's subject to pragmatic decision, unreliable networks, fads and fashions, and so on. When specifying the abstract information space, you cannot define it in terms of its access implementation. Just define the abstract information space, and leave it to the market to decide on how to access it.
> 
> You may well be right about this, but I'd like to see how far we can
> push it and what we'd get from doing so.

What's your reason for wanting to make this normative rather than just a declared good practice?

I take it that a TriG file would be non-conforming if it contains a named graph that doesn't match what you get by dereferencing?

Let's say I have a TriG file <x.trig>. Now let's assume a scenario A where it is conforming (the web matches its contents) and a scenario B where it's non-conforming (the web doesn't match its contents). What observable difference in the behaviour of software would you like to see?

For example, would a TriG parser generate the same RDF dataset in both cases or not?

Would a SPARQL processor answer all queries in the same way or not?

Would it entail the same additional triples/quads under the various levels of RDF/S and OWL entailment or not?

> I think we can make it a lot more crisp than AWWW.

That sounds like TAG business to me.

>> The relationship between <u,G> in a named graph shouldn't be “dereferencing u yields G”. It should be “owner of u gets to say what's in G”, which already *is* the case per AWWW, so we don't actually need to say anything about that when specifying <u,G>.
> 
> Can you say more about this?  I don't understand.   That seems even more
> abstract than dereference.    

It says: “Good practice: don't squat in other people's namespaces.”

> In practice, the owner of u gets to
> control what happens when folks dereference it, but without dereference
> I'm not sure the world cares who the "owner" is or really gives them any
> special rights.

That sounds completely wrong to me. In practice, the social convention of URI ownership is relied on in many places without assuming (or sometimes while forbidding) dereferencing: XML namespaces, URNs, microdata vocabulary URIs, …

Best,
Richard
Received on Friday, 7 October 2011 15:57:31 GMT

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