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

From: Jonathan Borden <jonathan@openhealth.org>
Date: Tue, 16 Jul 2002 11:13:38 -0400
Message-ID: <00b101c22cdb$5cea63c0$0201a8c0@ne.mediaone.net>
To: "Drew McDermott" <drew.mcdermott@yale.edu>, <www-rdf-logic@w3.org>
Cc: <www-rdf-comments@w3.org>

Drew McDermott wrote:

>
>    We have:
>
>       <bag1> rdf:_1 "10" .         (1)
>       <bag2> rdf:_1 "10" .         (2)
>    |=
>       <bag1> rdf:_1 _:l .          (3)
>       <bag2> rdf:_1 _:l .          (4)
>
> I don't see why (1) and (2) entail (3) and (4).  We've agreed that
> literals without datatyping information could mean anything at all.
> So how can we conclude that the first "10" denotes the same thing as
> the second "10"?

Suppose we define the infinite set of things denotes by "10
" as "_:1"

then (3)+(4) follow from (1)+(2)

>
>    We have a cardinality constraint of max 1 on rdf:_1.
>
>    Now add some new triples:
>
>       <bag1> rdf:_1 _:a1 .
>       _:a1   <foo:decimal> "10" .

and so the formerly infinite set of things denoted by "10" becomes the
singleton set which is "10" interpreted as a decimal number according to
foo:decimal (if that is what foo:decimal means of course).

>
>    This is consistent with (1) above and the cardinality constraint, and
also add:
>
>       <bag2>  rdf:_1 _:a2 .
>       _:a2    <foo:binary>  "10" .
>
>    This is consistent with (2) above and the cardinality constraint.
>
>    All together the added statements are consistent with (1) and (2)
above,
>    but not with with (3) and (4) above.

Yes so this is nonmonotonic. The nonmonotonicity is not intrinsic to
datatyping, particularly datatyping done at parse time or at XML Schema
validation time, rather it appears a characteristic of the desire to use RDF
triples to carry both syntax (i.e. the syntax necessary for datatyping) and
semantics.

Jonathan
Received on Tuesday, 16 July 2002 11:28:31 GMT

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