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Re: Strange behaviour of datatypes test A1 with answer yes and literals untidy

From: Drew McDermott <drew.mcdermott@yale.edu>
Date: Fri, 19 Jul 2002 17:59:30 -0400 (EDT)
Message-Id: <200207192159.g6JLxUo13697@pantheon-po01.its.yale.edu>
To: www-rdf-logic@w3.org


>    [Jonathan Borden]
>    Suppose we define the infinite set of things denotes by "10" as "_:1"
>
>    then (3)+(4) follow from (1)+(2)

   [me]
   >This is not the first time I've seen the idea that a literal might
   >denote more than one thing (or a set of things, or even an infinite
   >set of things).
   >
   >Where did this idea come from?  It seems quite counterintuitive to me.
   >I can't find it in the RDF(S) model theory either.

   [Pat Hayes]
   Its been in and out of it in various drafts. IT is a widely popular 
   idea, eg people write things like

   Jenny ex:age "10" .

   and expect that

   ex:age rdfs:Range xsd: integer .

   will be enough to force that literal to mean ten (not '10').  It 
   doesnt seem to me to be wildly unintuitive to say that a literal acts 
   like a name whose referent depends on the datatyping context (and 
   when there is no such context, it acts like an existential.)

No, that's not a problem.  But then a literal (occurrence) doesn't
denote an infinite set at all.  The right thing to say is that there
are an infinite number of models, and a given literal occurrence could
denote something different in all of them (or something close to
that).  But then the entailment in question:

       <bag1> rdf:_1 "10" .         (1)
       <bag2> rdf:_1 "10" .         (2)
    |=
       <bag1> rdf:_1 _:l .          (3)
       <bag2> rdf:_1 _:l .          (4)

still doesn't work, because for any given model nothing says the two
occurrences of "10" denote the same thing.  (Or so say we untidyists.)

                                             -- Drew McDermott
Received on Friday, 19 July 2002 17:59:39 GMT

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