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Re: ISSUE-61 (IRI-Casts): Casting to/from rif:iri [DTB]

From: Jos de Bruijn <debruijn@inf.unibz.it>
Date: Tue, 10 Jun 2008 19:22:10 +0200
Message-ID: <484EB842.3060304@inf.unibz.it>
To: kifer@cs.sunysb.edu
CC: Rule Interchange Format Working Group WG <public-rif-wg@w3.org>

Well, it was the only reasonable alternative I could think of for 
casting IRIs to strings.

I am personally actually not convinced that we even need such a casting 
function, but there are some people who think it is useful.

Best, Jos

Michael Kifer wrote:
> This makes iriToString a multivalued function (i.e., the same iri has several
> string interpretations). Is this what we want?
> 
> 
> 	--michael  
> 
> On Tue, 10 Jun 2008 16:40:04 +0200
> Jos de Bruijn <debruijn@inf.unibz.it> wrote:
> 
>> See [1] and preceding the messages in the thread for a description of 
>> the semantic problems.  In [1] I also proposed a casting predicate that 
>> seems to work.
>>
>> In summary, the biggest semantic challenge in casting IRIs to strings is 
>> that several different IRIs may be mapped to the same string.  The 
>> following was my proposal:
>>
>> "Let I be an interpretation, let u be an element in the domain of I, and
>> let {i1, ..., in} be the set of IRIs that denote u, i.e. for each ij (1
>> <= j <= n), IC(ij)=u.  IR(iriToString)(u,"ij")=t for (1 <= j <= n);
>> IR(iriToString)(u,s)=f for every element s not in {"i1", ..., "in"}."
>>
>> The rule set
>> iriToString("b"^^rif:iri,"b"^^xsd:string)
>>
>> is satisfied in every RIF interpretation.
>>
>> I think this predicates should be sufficient for most of the use cases.
>>
>>
>> Best, Jos
>>
>> Rule Interchange Format Working Group Issue Tracker wrote:
>>> ISSUE-61 (IRI-Casts): Casting to/from rif:iri [DTB]
>>>
>>> http://www.w3.org/2005/rules/wg/track/issues/
>>>
>>> Raised by: Christopher Welty
>>> On product: DTB
>>>
>>> It is clear users of RIF dialects such as BLD will want to be able to convert (cast) instances of rif:iri to/from other datatypes, in particular strings and possibly rif:text.
>>>
>>> In general, a casting mechanism is not present in DTB and should be added.
>>>
>>>
>>>

-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
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Received on Tuesday, 10 June 2008 17:21:31 GMT

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