Re: new version of rdf:O)-> document

On May 29, 2009, at 1:39 PM, Peter F.Patel-Schneider wrote:

> From: Sandro Hawke <sandro@w3.org>
> Subject: Re: new version of rdf:O)-> document
> Date: Fri, 29 May 2009 12:52:15 -0500
>
> [...]
>
>>> I agree. This kind of micro-tweaking is just going to get people  
>>> more
>>> confused. And strictly, under this proposal, Peter is right: the
>>> conceptual model of RDF is not changed.
>>>
>>> What I think is true, and maybe should be said, is that with this
>>> particular datatype, the conceptual model **of datatyped RDF** is  
>>> non-
>>> stand... excuse me, unusual, in that this datatype seizes the domain
>>> of plain literals for its own syntax space, so that in this  
>>> datatyped
>>> RDF, plain literals are treated as typed. But if you don't use this
>>> datatype, RDF is *exactly* the same as it was.
>
> Again, this is not the case.  It is just that you use plain literals
> when you might have wanted to use literals typed with rdf:O)->.  These
> literals are still plain literals, both in any surface syntax and in  
> RDF
> graphs, they do not all of a sudden become typed literals.

Nyaughahide... grimmerfischlipft... yes and no. The trouble is, these  
terms 'plain literal' and 'typed literal' are both syntactic and  
semantic classifications. Of course the literals don't change their  
syntax: that is the whole point. Neither do they change their  
denotations. But their semantic status as typed literals does change,  
seems to me, when this datatype is in use. Or at any rate, if we say  
it doesn't, then someone might want to have two kinds of literal with  
identical syntax: plain plain literals, which are RDF plain literals  
in every sense, and typed plain literals, which have a special  
relationship to the datatype. And that doesn't seem like a sensible  
thing to want to say in anyone's book.

But whatever. It is such a fine point that I really don't think  
anything will break. What we might say is that 'being typed with this  
datatype' should always be treated as having the exact same meaning as  
'being a plain literal', in every sense: syntactically, semantically,  
and in all RDF or SPARQL processing.

Pat

>
>>> We could (?) say that  RDF APIs MAY treat plain literals as being
>>> identical to typed literals typed with this datatype, in order to
>>> facilitate interoperability with tools which actually use the
>>> datatype. But its just a MAY.
>
> Could, I suppose.  This might possibly be considered to be an  
> effective
> change of the conceptual model, in some sense, I suppose.  ... waffle
> ... waffle ... waffle ....
>
>> Those both sound pretty good to me, but I'm easy to please.  Peter,
>> Dave, are either of them improvements?  Anything else we need to do  
>> at
>> this point?
>
> I still think that "which allows plain literals can be treated in
> certain cases like typed literals" has to go.  I would just remove the
> clause.
>
> Section 4 may need a bit of change.  I would go for "syntaxes for  
> SPARQL
> basic graphs patterns" changing to "SPARQL syntaxes".  The last  
> sentence
> of the section also should be changed in my view.
>
>
>> I'm filing the OWL request for CR today, optimistically including
>> rdf:PlainLiteral.  My hope is that everyone can sign off on this  
>> text by
>> next Wednesday, and this can go to CR with the rest of the OWL specs.
>
> Optimist!
>
>>    -- Sandro
>
> peter
>
>

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Received on Friday, 29 May 2009 20:36:00 UTC