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Re: how to make ill-typed literals inconsistent - ISSUE 109

From: Pat Hayes <phayes@ihmc.us>
Date: Wed, 16 Jan 2013 13:44:26 -0600
Cc: "public-rdf-wg@w3.org" <public-rdf-wg@w3.org>
Message-Id: <BC053F3D-B6AC-4F17-AD39-46B70FAB5398@ihmc.us>
To: "Patel-Schneider, Peter" <Peter.Patel-Schneider@nuance.com>

On Jan 16, 2013, at 10:59 AM, Patel-Schneider, Peter wrote:

> During the call today there was some discussion of ill-typed literals.
> 
> *IF* one wants ill-typed literals to be inconsistent then one has to tweak the semantics.
> The effect is (roughly) to require that the interpretations for literals whose datatype is in the datatype map belong to the value space for that datatype.

This is already required. What is needed is to change the current condition for when the lexical form is not in the lexical space of the datatype map. The current semantics says that in this case, the literal is required to denote something ouside LV. I propose to change this so that ill-typed literals simply do not denote at all. (This is more natural in any case: the current not-in-LV condition is artificial.) The main semantic conditions for RDF then make any triple containing such a literal false. The only serious change to the basic semantics is to allow the IL map to be partial. This looks like it might make RDF into a free logic, and it would if there were any quantifiers, but as there aren't, it seems safe. 

Pat


>  This looks a lot like the situation where that literal is range-required to be in the datatype.
> 
> As far as wording goes, RDF semantics would change something like:
> 
> Current:
> if <aaa,x> is in D then for any typed literal "sss"^^ddd in V with I(ddd) = x , 
> if sss is in the lexical space of x then IL("sss"^^ddd) = L2V(x)(sss), otherwise IL("sss"^^ddd) is not in LV
> 
> Revised:
> if <aaa,x> is in D then for any typed literal "sss"^^ddd in V with I(ddd) = x , 
>  IL("sss"^^ddd) is in LV
> if <aaa,x> is in D then for any typed literal "sss"^^ddd in V with I(ddd) = x , 
> if sss is in the lexical space of x then IL("sss"^^ddd) = L2V(x)(sss), otherwise IL("sss"^^ddd) is not in LV
> 
> This may look odd, but the net result is that there can be no models for ill-typed literals.


> 
> 
> Note:  I'm not here an advocate for this change, just noting how it could be done.
> 
> peter
> 

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Received on Wednesday, 16 January 2013 19:44:52 GMT

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