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Re: [XSCH/ALL] straw poll options

From: Benjamin Nguyen <Benjamin.Nguyen@inria.fr>
Date: Mon, 28 Nov 2005 18:00:51 +0100 (CET)
To: "Jeff Z. Pan" <jpan@csd.abdn.ac.uk>
cc: SWBPD <public-swbp-wg@w3.org>
Message-ID: <Pine.LNX.4.44.0511281750040.15376-100000@login-linux.inria.fr>

On Mon, 28 Nov 2005, Jeff Z. Pan wrote:

> 
> 
> Let me clarify the two proposals.
> 
> 1) Primitive equallity: all XML Schema datatypes have disjoint value spaces.
> 
> 2) Primitive equality extended with approximate mappings (easlier known as "leave it to the application"): it is more general than 1). Now all XML Schema datatypes have disjoint value spaces, plus applications can specify some approximate mappings, such as mapping "1.3"^^xsd:float to "1.3"^^xsd:double.

Surely a best practice would be to ask applications **not** to map 
xsd:float to xsd:double, but allow xsd:double to xsd:float, or any type 
promotion legal wrt XPath, or at least suggest something, such as 
returning the fact the result was calculated using an approximate mapping.

 > 
> Note that in this case, the values of "1.3"^^xsd:float and "1.3"^^xsd:double are different, but the approximate mapping **enables** the use of the XPATH eq operator, such as in the following SPARQL query:
> 
> > SELECT  ?size
> > WHERE   { eg:car eg:engineSizeInLitres ?size .
> >           FILTER (?size = xsd:decimal("1.3") ) . }
> 
> Using 2), "1.3"^^xsd:float and "1.3"^^xsd:double could be  results of the above query with the help of approximate mappings.
> 
> Another benefit of 2) is interoperability. Consider the scenario where one map ontology use xsd:float as the range of milage while the other use xsd:double. Using 1), milages in all different. While using 2), approximate mappings allows applications to do some useful things.

Fully agree with benefits.

> 
> We have briefly addressed how to formalise the approximate mappings in our draft, see:
> 
> http://www.w3.org/TR/swbp-xsch-datatypes/#sec-values-eq

See my previous comments (and Jeremy's comments ) at :

http://lists.w3.org/Archives/Public/public-swbp-wg/2005Nov/0055.html

> 
> Finally, the 2) approach is not non-monotonic. Even if we map"1.3"^^xsd:float to "1.3"^^xsd:double, their interpretations are still different. It would be non-monotonic if their interpretations became equal to each other after the mapping.

Unsure here, will detail later.

> 
> Jeff
> 
> --
> Dr. Jeff Z. Pan (http://www.csd.abdn.ac.uk/~jpan/)
> Department of Computing Science, The University of Aberdeen
> 


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Received on Monday, 28 November 2005 17:01:18 GMT

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