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Re: why I don't like named graph IRIs in the DATASET proposal

From: Richard Cyganiak <richard@cyganiak.de>
Date: Tue, 4 Oct 2011 16:37:11 +0100
Cc: Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>, "public-rdf-wg@w3.org" <public-rdf-wg@w3.org>
Message-Id: <E55D2770-ED93-4082-93A5-429AD21383D0@cyganiak.de>
To: Pat Hayes <phayes@ihmc.us>
Hi Pat,

On 3 Oct 2011, at 02:27, Pat Hayes wrote:
> There is no "way" of denoting something. To say that A denotes B is simply to say that A is being used as a name to refer to B. 

We're writing a technical specification. This means we get to define what we mean when we use a word. “To denote” in RDF can have a specific technical definition that can have caveats or complications not found in the usual meaning of the word, as long as we define our terms.

We regularly use words such as “resource”, “triple”, “subject” or “literal” with specific narrow technical definitions that differ from the usual definitions of these words.

This is common in standardization work, and given the time you've spent in standardization bodies I shouldn't have to explain that to you.

> If an identifier of some kind is being used to refer to some thing, whatever the thing is, then it is being used to, and can correctly be said to, DENOTE that thing. That is what the word "denote"  MEANS.

No. To say that A denotes B means whatever the specification defines it to mean. It can differ from what's written in a logic textbook.

> RDF will continue to be a notation with a normative model-theoretic semantics in which the IRIs in RDF triples are all treated as denoting names, and the truth of triples is defined in terms of that these names denote.

How about this: RDF *graphs* will continue to be a notation with a normative model-theoretic semantics, etc.

RDF datasets, however, will be simple semantics-free collections of RDF graphs where these graphs happen to be associated with IRIs to ease their management.

My demand is that *nothing* is changed in RDF Semantics as a result of the introduction of RDF datasets.

> (unless we somehow impose some extra semantic conditions to achieve the necessary lock on what the IRI denotes, as described in the original named-graph paper.) 

I think that this “lock” on what the IRI denotes is unnecessary and would be harmful and should be strictly avoided. RDF is being used to make statements about all sorts of things – people, web pages, taxonomic concepts, and so forth – without having any of this kind of “lock” in RDF Semantics. Why should graphs be any different? What's the use case?

Best,
Richard
Received on Tuesday, 4 October 2011 15:37:49 GMT

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