Re: A summary of the proposal for resolving the issues with rdf:text --> Could you please check it one more time?

On May 21, 2009, at 12:44 PM, Dave Reynolds wrote:

> Pat Hayes wrote:
>> On May 20, 2009, at 4:17 PM, Axel Polleres wrote:
>
>>> Undoubtedly, we are facing here some fundamental problems, which  
>>> seem to
>>> be not restricted to RDF text alone, but in general to the  
>>> extensibility
>>> of datatypes and D-entailment.
>
>> ** If you are right, surely the issues should be being followed by  
>> a wider audience than this small group? **   But it seems to me  
>> that the main issue is why we need to be using datatypes for plain  
>> literals *at all*. I have never seen this point made explicitly, or  
>> seen what the arguments are. Maybe this all took place inside the  
>> OWL and RIF groups, of course, but it would be useful to have the  
>> reasons made public, if only to help inform the technical  
>> discussions. After all, the most elegant solution to this whole  
>> matter, from the point of view of interoperability, would be for  
>> both OWL 2 and RIF to allow RDF literals as they are, without  
>> transcribing them into a different syntax, and make appropriate use  
>> of them. They are syntactically simple, easy to recognize, and  
>> semantically transparent. Previous SWeb standards (RDFS, OWL,  
>> SPARQL) have all accommodated to them without breaking. What has  
>> changed? Why do we need to be having this conversation? I have been  
>> told by various RIF and OWL2 WG members that the RDF literal design  
>> is "broken", "a mess", "a bad design", etc.., but nobody has  
>> explained what actual problems it creates, other than a failure to  
>> be theoretically elegant.
>
> At the risk of confusing things further ... I don't believe RIF at  
> least is trying to "fix" RDF lang-tagged literals.
>
> Recall that RIF is not an RDF application, it is a standard for  
> rules interchange and does not require the data such rules work on  
> to be in RDF. From the point of view of compatibility with the rules  
> languages that are to be interchanged the easiest design was to have  
> all literal constants have an associated datatype.  So rif:text was  
> something purely internal to RIF.
>
> Now RIF does include a specification (SWC) for how RIF/RDF  
> combinations are to be interpreted. This identifies a correspondence  
> between RDF plain literals with lang tags and RIF constants of type  
> rif:text (as was).
>
> This seems to me harmless. The datatype is something internal to RIF  
> translators, the datatypes don't leak into the RDF. There was no  
> notion that rif:text should be a datatype that RDF processors would  
> ever see or need to care about.
>
> The problems arise with the entirely well-intentioned unification of  
> rif:text with OWL 2's similar proposed datatype and its elevation to  
> a standalone spec. That leaves the standalone rdf:text spec trying  
> to draw a correspondence to RDF lang-tagged plain literals outside  
> the scope of a framework like RIF SWC which limits where and how  
> that correspondence applies.

OK, thanks for that clarification (though I have to say, I am  
**amazed** that RIF saw itself as RDF-independent. What WERE you guys  
thinking? Are you on the same planet as the rest of us? Oh well,  
onward...)

Actually, this makes the proposal to treat rdf:text as a retrospective  
'typing' of RDF plain literals even more plausible for RIF, seems to  
me. So I get the distinct sense that things are falling neatly into  
place here.

Pat

>
> Dave
>
>
>
>

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Received on Friday, 22 May 2009 00:41:21 UTC