Re: ISSUE-148: RDF Concepts - IRIs do *not* always denote the same resource

Hi David,

On 13 Dec 2013, at 19:23, David Booth <david@dbooth.org> wrote:
> No, I cannot live with this.  The current draft of the RDF Concepts says:
> 
>  "IRIs have global scope: Two different appearances of an
>  IRI denote the same resource.
> 
> and that is simply misleading and false, as explained here:
> http://lists.w3.org/Archives/Public/public-rdf-comments/2013Dec/0073.html

PLEASE, PLEASE, PLEASE don’t do this. 

It is true that an IRI can denote different things in different interpretations. But we are talking here about a brief and *informative* introduction to semantic web architecture of two pages. It cannot, and should not, get into the business of explaining interpretations and possible worlds.

So we are concerned here with only one possible world, the one we live in. In this particular possible world, an IRI denotes the same thing wherever it occurs. For the vast majority of readers, this is all they ever need to know.

Now, you are right, RDF Semantics introduces the notion of interpretations, and an IRI can denote different resources in different interpretations. But this denotation of different resources is not even a *feature*. It is simply part of the formalism that happens to be used to define what entailments are correct. Had the semantics been formally defined using inference rules rather than model theory, then the phrase you quote would be absolutely correct.

In summary, David, you give us two alternatives.

a) Either we need to introduce a brief informative account of the way IRIs work on the semantic web with caveats about multiple possible worlds.
b) Or we can’t tell people that an IRI that occurs twice should always be taken as identifying the same thing.

Either option is harmful to the intended audience of RDF Concepts. All in the name of being *technically* correct.

Again, it’s a *non-normative* section, it’s the *introduction*, it’s intended to be understandable by people who will never look at RDF Semantics, and the sentence is even true within any given single interpretation!

Best,
Richard

Received on Friday, 13 December 2013 21:52:11 UTC