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Re: DTB status (on today's agenda)

From: Jos de Bruijn <jos.debruijn@deri.org>
Date: Fri, 02 May 2008 15:29:51 +0200
Message-ID: <481B174F.9090600@deri.org>
To: Sandro Hawke <sandro@w3.org>
CC: Michael Kifer <kifer@cs.sunysb.edu>, Axel Polleres <axel.polleres@deri.org>, "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>



Sandro Hawke wrote:
>> Let me reiterate (for the third time) my extremely simple compromise
>> proposal.  Here expand(foo) means substitute with the prefix definition of
>> foo.
>>
>> 1. Standalone occurrence:
>>     foo:bar ---> "expand(foo)bar"^^"http://www.w3.org/2007/rif#iri"
>>
>> 2. A ^^-occurrence:
>>     "abc"^^foo:bar ----> "abc"^^"expand(foo)bar"
> 
> I can live with this, if we don't use "^^".   This was the second option
> in my e-mail, although I accidentally expanded bar as well.
> 
> The problem with ^^ is that it's very distinctive and is used in other
> semantic web languages.  But in those languages, it's followed by a URI
> constant not a string constant.    So I'd have to object that re-using
> ^^ with this kind of type difference is too confusing to users.

I thought that in RIF ^^ is also always followed by an IRI constant?

I think we should stick with the ^^ in RIF, because its use actually 
generalizes the use in the other semantic Web languages.

Best, Jos

> 
> In my previous e-mail I wrote  a^^b as lit(a,b), which seems about
> right.   I'm not sure what we should call "lit".   SWI-Prolog calls in
> "type(b, a)". [1] 
> 
> I suppose the obvious thing is "Const", so the change in the grammar is:
> 
> Remove:
> 
>    Const          ::= '"' UNICODESTRING '"^^' SYMSPACE
> 
> Add (trying to keep current style):
> 
>    Const          ::= 'Const(' '"' UNICODESTRING ',' '"' SYMSPACE '"' ')'
> 
> Does that work?
> 
> I'd also consider putting the symspace first (as in SWI-Prolog), because
> in a sense it's the most-significant part.
> 
>> If you do not like "..." for the after the ^^-part, use '...' or even <...>.
>> But, in the latter case, <...> CANNOT be used as a macro. That is,
>>
>>    <abc>  --X--> "abc"^^rif:iri.
>>
>> is a no-no.
>>
>> My proposal allows some simple form of context sensitivity, but not the
>> above <...> macro atrocity (if <...> is also used after the ^^).
>> I do not see why we need such a macro in the first place, if in most cases
>> we will be using foo:bar.
> 
> I can't think of any reason we need "<" ... ">", but we might.   I think
> we can leave them out until/unless we need them.
> 
>       -- Sandro
> 
> [1] http://www.swi-prolog.org/packages/rdf2pl.html#sec:3.1
> 

-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
----------------------------------------------
An expert is a person who has made all the
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Received on Friday, 2 May 2008 13:30:04 GMT

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