W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > November 2002

Re: do bad datatype literals denote [was Re: Datatype test cases ...]

From: pat hayes <phayes@ai.uwf.edu>
Date: Wed, 20 Nov 2002 14:39:22 -0600
Message-Id: <p05111b12ba01a1f7b4fd@[10.0.100.86]>
To: Dave Beckett <dave.beckett@bristol.ac.uk>
Cc: w3c-rdfcore-wg@w3.org

>  >>>Brian McBride said:
>>  At 14:49 20/11/2002 +0000, Jan Grant wrote:
>>  [...]
>>  > > We know that:
>>  > >
>>  > >   <a> <b> "foo"@@en#<datatype> .
>>  > >   <c> <d> "foo"@@fr#<datatype> .
>>  > >
>>  > > entails
>>  > >
>>  > >   <a> <b> _:l .
>>  > >   <c> <d> _:l .
>>  > >
>>  > > for all datatypes except rdf:XMLLiteral.
>>  >
>>  >It does? Doh.
>>
>>  I think so, but don't take my word for it.  Jeremy?
>>
>>  >I still think that's broken; but I'll fix the test case.
>>  >Basically these cases outline the various issues - I'll correct them as
>>  >appropriate.
>>
>>  Nah - see below - you got it right unless we know that datatype is not
>>  rdf:XMLLiteral.  We know its not called that, but unless we make a unique
>>  name assumption, we don't know that its not another name for the same thing.
>
>I also think it is broken - hard to implement in a efficient fashion.
>(And the N-Triples syntax above is wrong; ^^ not #)
>
>Typed literals should be opaque nodes with identity, like URI-refs.
>Looking at parts of them for RDF interpretations is wrong.  This
>"ignoring the language in datatype interpretation except for
>rdf:XMLLiteral" is seeming increasingly stupid.

I tend to agree. Having XML literals as datatypes doesn't seem to 
help with anything and its starting to create new problems, because 
so many things are special to this case, not the least being that it 
alone is in RDF.

BTW, one thing I still don't have clear is what it is exactly that an 
XMLLiteral is supposed to denote. What is the value space of the 
datatype?? I used a form of words in the recent semantics doc that 
was so recondite that I thought one of the reviewers would have 
complained, but I'd rather say something simple and honest.

>
>If it said:
>   [[
>      <a> <b> XXX .
>      <c> <d> XXX .
>
>    where XXX is any legal syntax for typed literal object node
>
>    entails
>
>      <a> <b> _:l .
>      <c> <d> _:l .
>   ]]
>
>Then it would make more sense to me.

Yes, but that follows from the basic graph syntax MT, ie its a simple 
entailment. Nothing particularly to do with datatypes or lang tags.

Pat
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Received on Wednesday, 20 November 2002 15:39:26 EST

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