Re: "do not occur"

Peter F.Patel-Schneider wrote:
> From: Sandro Hawke <sandro@w3.org>
> Subject: "do not occur"
> Date: Tue, 2 Jun 2009 12:00:54 -0500
> 
>> [FYI, today, SPARQL and RIF said they're okay with the current drafts;
>> in RIF's case, this is modulo the name change being made in the
>> builtins.]
>>
>> At the risk of waking sleeping dragons, Axel and I were talking about
>> this delicate sentence:
>>
>>     Therefore, typed literals with rdf:PlainLiteral as the datatype do
>>     not occur in syntaxes for RDF graphs, nor in syntaxes for SPARQL.
>>
>> and how it seems normative, even though it's stated as purely logical.
>>
>> The confusion, as I understand it, is that typed literals with the
>> datatype rdf:PlainLiteral:
>>
>>         - DO NOT occur in the syntax, which means they
>>         - MUST NOT occur in the documents.
>>
>> This is a little confusing.
>>
>> Option 1:
>>
>>     leave it as is
>>
>>      (my vote: +0)

> +1

-1

To me this last sentence indicates that if I now go out and publish a 
graph.

      :s :p "gotcha, haha"^^rdf:PlainLiteral.

I consequently yield the whole spec invalid (by ex falso quod libet)....

There is no guarantee that there is no such graph published out there 
already.  Current RDF APIs swallow that graph without trouble, I can 
even write SPARQL queries against it that filter the datatype 
rdf:PlainLiteral with current implementations) and it is totally 
compliant with RDF. So, the sentence as it stands just doesn't make 
sense to me.


> I put the sentence in to emphasize the previous sentence, which provides
> the normative force.  That sentence as well does not use a MUST, also by
> design.  The rationale is that this is the way that things are.

Let us have a look at the previous sentence again:

"To eliminate another source of syntactic redundancy and to retain a 
large degree of interoperability with applications that do not 
understand the rdf:PlainLiteral datatype, the form of rdf:PlainLiteral 
literals in syntaxes for RDF graphs and for SPARQL is the already 
existing syntax for the corresponding plain literal, not the syntax for 
a typed literal."

Hmm, to my understanding that sentence indicates only that a 
rdf:PlainLiteral typed literal is not a plain literal in the sense of 
this spec not that rdf:PlainLiteral typed literals
do not exist - which however the other sentence does say. At the very 
least, I find the second sentence more confusing than enlightning in its 
current state.


> A MUST
> would be directives to implementations, and this is not that. 

>> Option 2:
>>
>>     rephrase as: Therefore, typed literals with rdf:PlainLiteral as the
>>     datatype are considered by this specification to be not valid in
>>     syntaxes for RDF graphs or SPARQL.
>>
>>     (my vote: -0)


+1

This is precise and on the safe side. I have a much better feeling with 
that.

> +0
> 
>> Option 3:
>>
>>     (just drop the sentence; it's doesn't add much itself.)
>>
>>     (my vote: +1)
> 
> +0

+0 I can live with that, although indeed the sense of the sentence 
before is a bit lost with that, i.e. it doesn't say anything about 
explicitly rdf:PlainLiteral typed literals.

>> That's it.  (Dear sleeping dragons: If you're going to breath fire,
>> please give me time to run away first.)
> 
> But sleeping dragons don't work that way.  :-)

(I guess after that mail, you are safe Sandro, they'll run after me :-))

Axel

>>        -- Sandro
> 
> peter
> 
> 


-- 
Dr. Axel Polleres
Digital Enterprise Research Institute, National University of Ireland, 
Galway
email: axel.polleres@deri.org  url: http://www.polleres.net/

Received on Tuesday, 2 June 2009 20:13:31 UTC