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Re: Action-48 text: a New Plan for plain literals

From: Pat Hayes <phayes@ihmc.us>
Date: Mon, 23 May 2011 20:22:31 -0500
Cc: public-rdf-wg@w3.org
Message-Id: <4B599272-A950-4E44-BB2A-036DC55B4EB9@ihmc.us>
To: Jeremy Carroll <jeremy@topquadrant.com>

On May 23, 2011, at 1:10 PM, Jeremy Carroll wrote:

> -0
> 
> I don't really see what the problem rdf:LanguageTaggedLiteral is trying to solve.

The problem is that without this (or something like it), there are RDF literals which are dissimilar to any other literal but have no type. So it is impossible to, for example, talk about the class of their values, to restrict queries to them, etc.. This problem - of literals with no type - was one the motivations for rdf:PlainLiteral in the first place. The new proposal takes some plain literals (without tags) and assimilates them to xsd;string, which cannot (for XSD reasons external to RDF) accept the values of tagged literals. So we need a type for those values, which are found nowhere else in RDF and need a home, and cannot be banned because i18n and Reuters, among others, want them. 

> The problem that I understood with the RDF 2004 specs in this area was that plain literals without lang tags and xs:string were identified by some systems and not by others. This problem is solved by the proposal.
> 
> I believe a simpler proposal which basically leaves language tagged literals unchanged would also solve the xs:string problem.

We do not propose to change any literals in any concrete RDF syntax. 

I do not believe there is a simpler solution which assimilates plain strings to xsd:string and also gives a type to all RDF literals. If we were to instead assimilate xsd:string to plain untagged literals, it is possible; but this would require a change to SPARQL and appears to not be a popular solution. Similarly, deprecating everything in favor of  rdf:PlainLIteral would work, but isn't going to fly because nobody wants to deal with those trailing '@' s

Pat

> 
> Jeremy
> 
> 
> 
> On 5/22/2011 8:01 PM, Pat Hayes wrote:
>> The proposal outlined in the wiki here
>> 
>> http://www.w3.org/2011/rdf-wg/wiki/StringLiterals/LanguageTaggedLiteralDatatypeProposal
>> 
>> completes Richard and my action item 48 from the last telecon.
>> 
>> Pat
>> 
>> 
>> ------------------------------------------------------------
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>> 40 South Alcaniz St.           (850)202 4416   office
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>> 
>> 
>> 
>> 
>> 
>> 
> 
> 
> 

------------------------------------------------------------
IHMC                                     (850)434 8903 or (650)494 3973   
40 South Alcaniz St.           (850)202 4416   office
Pensacola                            (850)202 4440   fax
FL 32502                              (850)291 0667   mobile
phayesAT-SIGNihmc.us       http://www.ihmc.us/users/phayes
Received on Tuesday, 24 May 2011 01:23:05 GMT

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