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RE: Literals (Re: model theory for RDF/S)

From: Peter Crowther <peter.crowther@networkinference.com>
Date: Tue, 2 Oct 2001 16:28:14 +0100
Message-ID: <B6F03FDBA149CA41B6E9EB8A329EB12D05A7F2@vault.melandra.net>
To: www-rdf-logic@w3.org
> From: Patrick.Stickler@nokia.com [mailto:Patrick.Stickler@nokia.com]
> > From: ext Peter F. Patel-Schneider 
[...]
> > Consider
> > 
> > #Susan #favorite-integer int:05 .
> > #Susan #favorite-integer int:5 .
> > 
> > how is an RDF query system supposed to respond when asked 
> > about Susan's favorite integers?
> 
> Good point. But again, that has nothing to do with the 
> proposed encoding
> of literals as URIs. The very same problem exists with
> 
>  #Susan #favorite-integer "05" .
>  #Susan #favorite-integer "5" .
>  
> Right?

Not necessarily.  It depends on whether 'int:' implies some special
processing that strips leading zeroes, or (with an approach that rohibits
semantically vacuous alternatives) whether the parser can recognise int:05
as prohibited and throw an error, or merely return undefined results.

> > ...A DAML+OIL (March 2001) processor has to 
> > understand a portion of
> > XML Schema, not just the syntax but also the semantics.
> 
> Really? I thought it just borrowed the URI defined identity of
> the XML Schema data types. I once asked if a DAML parser had
> to also include that subset of functionality of XML Schema
> for dealing with data types -- particularly user defined
> data types, and was told a clear "no". Not that it couldn't,
> but it didn't have to.
> 
> Maybe things have changed?
> 
> Do you know of any DAML system that presently does, or at 
> least plans to?

Network Inference's Cerebra inference engine [1] currently implements XML
Schema integers, floats, reals and (a subset of) strings.  Sean Bechhofer at
the University of Manchester has written a parser/renderer combination based
on OilEd [2] that converts DAML into our (currently rather peculiar)
extended version of FaCT [3] XML.  So... yes, sort-of.  It's held together
with string at the moment.  We plan to implement more complete support.

[1] http://download.networkinference.com/
[2] http://img.cs.man.ac.uk/oil
[3] http://www.cs.man.ac.uk/~horrocks/FaCT/

		- Peter
--
Peter Crowther, VP Development, Network Inference Limited
Received on Tuesday, 2 October 2001 11:29:02 GMT

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