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Re: [ontolog-forum] Extensional vs Intensional semantics for RDF/RDFS

To: ontolog-forum <ontolog-forum@xxxxxxxxxxxxxxxx>
From: John McClure <jmcclure@xxxxxxxxxxxxxx>
Date: Thu, 28 Nov 2013 11:24:26 -0800
Message-id: <5297986A.6070406@xxxxxxxxxxxxxx>
Hi Pat
>> <snip/>
>> Where can I find more information about the fourth part of the quad. I'm
>> assuming that's to point to a provenance object defined by the PROV
>> standard
> That assumption illustrates the basic problem: there is no way to standardize 
>the multifarous potential uses for the fourth quad field. To my knowledge it 
>has been used as a graph label, as an extra relational parameter, to encode a 
>time reference, to indicate a source (but not using PROV: that usage pre-dates 
>PROV by several years, maybe a decade), and simply as an indexing mechanism 
>inside a quad store. I am sure that there are others. So, implementations use 
>it (and some even use quints) but its not part of any normative RDF standard 
>because it doesn't have a coherent semantics.
I'm wondering if a semantic is even needed for a 'quad field' that 
points to PROV data -- provenance appears to me a different level of 
discourse, actually much like xml:lang, which (merely?) happens to be a 
field in a DC provenance description.... it seems to me that if items 
like xml:lang are /not captured/ within a PROV/DC then yes, the 
alternative is /major chaos/ as quads give way to quints whic give way 
to ... these higher order "ints" can be performance-savvy for database 
operations, but questionable from an interchange perspective.    (01)

A standardized PROV/DC addition to rdf:Statement seems reasonable to me, 
perhaps best not as a property value but in some other way. A somewhat 
common use for a quad-field I've seen is to name a/the DAG in which the 
triple exists, but this could be as easily the content of a "publisher" 
or "subject" field within a provenance description.    (02)

I need to find time to dig into the PROV spec, maybe this is 
covered..Thanks/jmc    (03)

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