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Re: Minimal dataset semantics

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Thu, 23 Aug 2012 16:36:51 -0400
Message-ID: <50369463.8010701@gmail.com>
To: Richard Cyganiak <richard@cyganiak.de>
CC: RDF Working Group WG <public-rdf-wg@w3.org>
I vote for a).

peter

On 08/23/2012 11:06 AM, Richard Cyganiak wrote:
> If we define a semantics for datasets at all, it should be such that:
>
> 1. It formalizes what is denoted by graph IRIs
> 2. Interesting semantic extensions can be made by third parties or future WG
> 3. It doesn't preclude any reasonable semantic extensions
>
> The problem with the quoting semantics is that it fails #3. The quoting semantics makes it a contradiction if dataset A and dataset B contain the same graph IRI with different associated graphs. We cannot do semantic extensions that produce useful additional entailments from a contradiction.
>
> No other proposed semantics does have that problem. All of the other proposed semantics can be easily extended with an additional clause that requires equal graph names to be associated with equal graphs.
>
> Therefore, the quoting semantics is *not minimal*. Quite the opposite. It is not a "weak" semantics at all, because it makes it very easy to derive contradictions, and contradictions are *very strong* semantic effects.
>
> I also agree with Antoine that formalizing the notion of "no semantics" is pointless.
>
> My conclusion is that our viable options are:
>
> a) to say nothing regarding the semantics of datasets, or
> b) to define a minimal version of a "truth-based"/"entailment-based" semantics (where [[ :i1 { G } ]] entails [[ :i1 { G' } ]] if graph G entails graph G').
>
> Best,
> Richard
Received on Thursday, 23 August 2012 20:37:29 UTC

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