Re: RIF Minutes for 21-Aug-07-rif-minutes.html

>>>>>>>> Axel: Strings with @ signs in RDF - will this be OK in the proposed 
>>>>>>>> format for such literals?
>>>>>> The original proposal was that the text type is a pair of lexical form 
>>>>>> and language code. The XML syntax would use attributes for the language 
>>>>>> code as normal. For the presentation syntax (but see below) I'd suggest 
>>>>>> following N3/Turtle:
>>>>>>
>>>>>>             "string"@lang
>>>>>>
>>>>>> which would correspond to the literal value ("string", lang)^^rif:text.
>>>>> For uniformity of the syntax, it is better to use "string@lang"^^...
>>>>> where @ is special (i.e., needs to be escaped, if one wants to include it
>>>>> in the string. 
>>>>> By the way, why can't we use xsd:string data type for these?
>>>> Because, in this case, it would be impossible to distinguish between
>>>> strings with a '@', and strings with a language tag.
>>> No. Read again about having @ a special symbol that needs to be escaped.
>> So, you propose to always escape it? It seems that you would then change
>> the xsd:string datatype, which is something we should avoid.
> 
> Perhaps using xsd:string is not the right way, since this type does not
> have the language specifier (right?).  

Correct.

> So, we should use a different data
> type. Perhaps rif:text or rif:istring. 

So we are in agreement.
I sent an email to the XSD folks earlier, to see whether/how such a
datatype could be aligned with the XML Schema datatypes.

> But the syntax should be uniform:
> "...@lang"^^rif:text.  Inside the "..." the @ sign should be escaped if it
> is not the language sign.

I have no problem with that; sounds reasonable.

> 
>>>>>>>> Jos: this is also a need to ask the XML schema group re such literal 
>>>>>>>> handling
>>>>>> Exactly, and we should wait until we have their comments before 
>>>>>> finalizing this part.
>>>>>>
>>>>>>>> Chris: 4 syntaxes in use: presentation + XML, ASN and "formal"
>>>>>> I've been meaning to raise this. That does seem rather a lot.
>>>>>>
>>>>>> The original argument for the presentation syntax was that it was needed 
>>>>>> to enable the semantics to be clearly presented. The bulk of the 
>>>>>> document now uses the formal syntax for this purpose.
>>>>>>
>>>>>> Do we still need the presentation syntax as well?
>>>>> The presentation syntax is basically the same as the formal syntax. We just
>>>>> give a BNF for it.
>>>> The current document (posted conditions) defines a formal syntax which
>>>> uses the common mathematical notation  you find in textbooks in the
>>>> definition of well formed formulas, but the uses the concrete syntax
>>>> (the one for which the BNF is given) in other places.  These are two
>>>> different syntaxes.
>>> The two syntaxes are basically the same.
>> I would suggest only presenting one of them in the document.
> 
> The presentation syntax is BNF of the formal syntax with a few more details
> that are to be used in the examples.  Using only XML for examples is a bad
> practice; makes documents incomprehensible.

I meant presenting either the formal syntax or the BNF syntax; I guess
we should go for the BNF syntax.
We should indeed not use only XML for the examples.

Best, Jos
-- 
Jos de Bruijn            debruijn@inf.unibz.it
                      http://www.debruijn.net/
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As far as the laws of mathematics refer to
reality, they are not certain; and as far as
they are certain, they do not refer to
reality.
  -- Albert Einstein