Abstract syntax VS concrete syntax [Was: Re: bad language tags]

The reason why concepts has the lower-case constraints is because it 
defines everything in terms of sets and set theory.

An RDF Graph is a set of triples. If a language-tagged string can have 
lower or upper cased language tag, then:

   <x> <y> "xxx"@en-US .

is a different triple than:

   <x> <y> "xxx"@en-us .

and therefore, a graph that has those two triples has 4 nodes, 2 
literals, etc.

There is no contradiction with what Turtle and other serialisations allow.

Similarly, IRIs MUST be absolute in RDF. Yet, a concrete syntax can 
allow relative IRIs inside its documents, because they are eventually 
parsed to absolute IRIs.

Same thing for escaped characters in IRIs: a concrete syntax can allow 
any UNICODE characters as long as they are parsed to escaped characters. 
All this should be explained in the "Parsing" section of the 
corresponding specification.
(Modern browsers do this for URLs, and are still conformant)


AZ



Le 07/05/2013 11:17, Andy Seaborne a écrit :
>
>
> On 07/05/13 09:09, Antoine Zimmermann wrote:
>> Le 07/05/2013 09:26, Andy Seaborne a écrit :
>
>>>>>
>>>>> Anything else is not a language-tagged string.
>>>>> So, it's answer 1.
>>>
>>> By that argument "@en-US" is a syntax error yet it is the canonical
>>> form.
>>
>> In the abstract syntax "@en-US" would be strongly wrong because of the @
>> character.
>
> I was using that to indicate a language tag, not that it is part of the
> language tag.
>
>> It does not need be a syntax error in Turtle, but it's an
>> error in RDF/XML
>
> You are saying that xml:lang="en-US" is an *error* in RDF/XML?
>
> See sec 2.7, Example 8 of the RDF/XML spec and the links to the example8
> files.
>
> and it links to
> http://www.w3.org/TR/REC-xml/#sec-lang-tag
>
>> or JSON-LD.
>
> All I can see is "Languages codes are defined in [BCP47]."  Link please.
>
>> One could imagine a syntax where en-US is a
>> syntax error.
>
> A parser produces a graph.  The Turtle spec (sec 7) does not say
> anything about changing the characters of LANGTAG.
>
> Let's conduct a survey:
>
> How many existing systems treat this
>
> ---------------
> <http://example/s> <http://example/p> "xyz"@en .
> <http://example/s> <http://example/p> "xyz"@EN .
> ---------------
> as one triple or as two triples aside from whether they treat the graphs
> as equivalent.
>
>
>      Andy
>
>

-- 
Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
France
Tél:+33(0)4 77 42 66 03
Fax:+33(0)4 77 42 66 66
http://zimmer.aprilfoolsreview.com/

Received on Tuesday, 7 May 2013 10:02:27 UTC