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

From: Michael Kifer <kifer@cs.sunysb.edu>
Date: Tue, 10 Jun 2008 13:24:39 -0400
To: Jos de Bruijn <debruijn@inf.unibz.it>
Cc: Rule Interchange Format Working Group WG <public-rif-wg@w3.org>
Message-ID: <20080610132439.05b7cfb8@cs.sunysb.edu>

I was just checking if this was the intent.

I think it is enough to define this function by a bunch of axioms

iriToStr("a"^^rif:iri  "a"^^xs:string).

and not bother with the preceding text in your message. It is much simpler that way.

michael

On Tue, 10 Jun 2008 19:22:10 +0200
Jos de Bruijn <debruijn@inf.unibz.it> wrote:

> 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.
> >>>
> >>>
> >>>
> 
Received on Tuesday, 10 June 2008 17:25:33 GMT

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