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Facet Nomenclature

From: Michael Schneider <schneid@fzi.de>
Date: Wed, 19 Nov 2008 14:58:56 +0100
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A0E06971@judith.fzi.de>
To: "W3C OWL Working Group" <public-owl-wg@w3.org>
Hi!

Currently, the RDF-Based Semantics differs significantly from the Direct Semantics and the Structural Spec regarding the facet related aspects of datatype maps. This complicates a proof of the correspondence theorem. I'm currently in the process of adjusting the RDF-Based Semantics accordingly. It seems to work quite well for the different concepts being used, but I have problems with the nomenclature.

The Structural Spec in

  <http://www.w3.org/2007/OWL/wiki/Specification#Datatype_Maps>

defines the following two relevant concepts:

  (1) The "facet space" N_FS(d): 
      This is the set of all facet/value pairs <F,V> 
      allowed for the datatype d.

  (2) The "facet value" (<F,V>)^FS: 
      This is the subset of the value space of the datatype d
      that results from applying the facet d with the value V to d.

Now, I am unhappy with calling (2) a "facet value". (1) already calls "V" the "value" of the facet F:

  "where F is a constraining facet 
   and is identified by a URI, 
   and V is an arbitrary object called a value."

So this is (almost) a name clash. But even without this name clash, calling the resulting /set/ a "facet value" is confusing, IMHO.

FWIW, I also call V a "facet value" or simply a "value" in the RDF-Based Semantics, and I don't see a better name for it.

I suggest to rename the set "(<F,V>)^FS". In the RDF-Based Semantics, I call it the "facet extension" of d, F and V. I am ok with using a different name, as long as it avoids the sort of confusion mentioned above.

Regards,
Michael

--
Dipl.-Inform. Michael Schneider
FZI Forschungszentrum Informatik Karlsruhe
Abtl. Information Process Engineering (IPE)
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Received on Wednesday, 19 November 2008 13:59:37 GMT

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