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Re: additional issue-57 use case: polysemy

From: Pat Hayes <phayes@ihmc.us>
Date: Tue, 5 Jun 2012 12:31:21 -0500
Cc: Jonathan A Rees <rees@mumble.net>, www-tag@w3.org
Message-Id: <C4D1DA4A-2933-464E-926F-DB5B38883C51@ihmc.us>
To: ht@inf.ed.ac.uk (Henry S. Thompson)

On Jun 5, 2012, at 11:23 AM, Henry S. Thompson wrote:

> ht writes:
>> One probably tangential query: [1] says
>>  "The extension graph, if provided, must be true under the semantic
>>   conditions of the extension."
>> This seems an odd constraint, if I read it correctly.  By construction
>> the reserved IRIs of an extension will all be _mentioned_ in its
>> extension graph.  But it seems unlikely that they will be _used_ in it
>> in most cases.
> OK, so now I've gotten to the example [2], and it indeed _uses_ what
> is clearly _intended_ to be the only IRI in the extension indicated by
> ex:TimeDependentProperty.  But the example extension graph, notated
>  { ex:TimeDependentProperty a rdfs:Class }
> in fact uses _three_ IRIs, namely "ex:TimeDependentProperty",
> "rdf:type" and "rdfs:Class", right?  So how do I know which of these
> is actually _in_ the extension?

All extensions extend RDF, so have the rdf: vocabulary in them. I am here assuming that TimeDependentProperty extends RDFS. This is a pretty conservative assumption. 

>  I.e. for which ones does their use in
> a graph which inherits ex:TimeDependentProperty require appealing to
> the constraints defined in that extension?

All of them. Extensions are nested in a global DAG of inheritance. In this example, we have RDF <= RDFS <= TimeDependentProperty, where <= indicates 'is inherited by'. So the TImeDependentProperty extension includes the RDF and RDFS vocabluaries with their meanings as specified by the 2004 semantic specs, with the addition that some properties can be time-dependent. (To be very careful, one would re-cast these as trinary relations and extend the 2004 semantics to apply to them appropriately. No doubt in a carefully prepared real life extension,t his would be worth doing.)


> ht
> [2] http://www.w3.org/2011/rdf-wg/wiki/AnotherSpin#examples
> -- 
>       Henry S. Thompson, School of Informatics, University of Edinburgh
>      10 Crichton Street, Edinburgh EH8 9AB, SCOTLAND -- (44) 131 650-4440
>                Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
>                       URL: http://www.ltg.ed.ac.uk/~ht/
> [mail from me _always_ has a .sig like this -- mail without it is forged spam]

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Received on Tuesday, 5 June 2012 18:36:55 UTC

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