Re: "do not occur"

On Tue, Jun 2, 2009 at 4:46 PM, Alan Ruttenberg
<alanruttenberg@gmail.com> wrote:
> On Tue, Jun 2, 2009 at 3:41 PM, Axel Polleres <axel.polleres@deri.org> wrote:
>> 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.
>
> Here's my interpretation of the spec: "haha"^^rdf:PlainLiteral is not
> a typed rdf:PlainLiteral literal.
> It means something, just not what you think. That's because the only
> syntax for rdf:PlainLiteral literals is that of plain literals.

Incidentally, the fact that you can filter using the DATATYPE function
in sparql is another hint that something is amiss. By my earlier
analysis, the DATATYPE function should never return rdf:PlainLiteral,
according to our spec.

-Alan

>
> -Alan
>
>> 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 20:49:21 UTC