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

From: Pat Hayes <phayes@ihmc.us>
Subject: Re: why I don't like named graph IRIs in the DATASET proposal
Date: Thu, 6 Oct 2011 11:06:07 -0500

> 
> On Oct 6, 2011, at 5:54 AM, Peter Frederick Patel-Schneider wrote:
> 
>> From: Pat Hayes <phayes@ihmc.us>
>> Subject: Re: why I don't like named graph IRIs in the DATASET proposal
>> Date: Wed, 5 Oct 2011 18:05:04 -0500
>> 
>>> 
>>> On Oct 4, 2011, at 10:08 AM, Richard Cyganiak wrote:
>>> 
>>>> On 2 Oct 2011, at 18:06, Pierre-Antoine Champin wrote:
>>>>> As you stress it, RDF does not dictate which IRI should denote which
>>>>> resource (including graphs). I don't think I ever suggested to change that.
>>>>> 
>>>>> However, RDF dictates that each time I use the same IRI (as a node), it
>>>>> denotes the same resource.
>>>> 
>>>> No, it doesn't.
>>> 
>>> Yes, it does. 
>> 
>> Are you sure, Pat, especially formally?
>> 
>> peter
> 
> Well, formally, it requires that any RDF graph has an
> interpretation. Now, suppose a URI U occurs in a graph G where it is
> (for reasons that need not detain us here) required to denote some
> thing, and also occurs in some other graph H where it is similarly
> required to denote some other thing, different from the first
> thing. Now consider the graph (G union H). If both requirements are in
> force, this graph cannot be given an RDF interpretation. Which
> violates the RDF semantics spec. So by modus tollens, those two
> requirements, taken together, violate the spec.  

Sure, in a particular interpretation of a graph there is a single
denotation for each IRI (in the graph).   However, I don't see anything
above carrying either of these conditions.

Different interpretations can have different denotations for the same
IRI in a particular graph.

I suppose that one could consider a single interpretation as it relates
to two different graphs, where, of course, there would be a single
denotation of each IRI, but the RDF Semantics doesn't consider this.  In
any case the set of interpretations for one graph may not be the same as
the set of interpretations of another.

[...]

> Pat

peter

Received on Friday, 7 October 2011 04:22:31 UTC