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Re: AtomList infinite or cyclic in all models

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Tue, 20 Feb 2007 14:49:17 +0000
To: Ian MacLarty <iml@missioncriticalit.com>
Cc: Bijan Parsia <bparsia@isr.umd.edu>, drew.mcdermott@yale.edu, www-rdf-rules@w3.org
Message-ID: <f5bodnovq8i.fsf@hildegard.inf.ed.ac.uk>

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Ian MacLarty writes:

> On Mon, Feb 19, 2007 at 12:10:14PM +0000, Henry S. Thompson wrote:

>> . . .
>> Then some further work is required to axiomatise a useful
>> definition of List and/or Sequence.  AtomList is also misleading as
>> a name in that there's no constraint that its members be atoms,
>> AFAIK!
>> 
> The allValuesFrom(Atom) restriction on rdf:first ensures that all
> elements of AtomList are Atoms.

Ah, thanks, I missed that.

Still not clear why cons pairs are the right way to model lists of
anything, atoms or otherwise, in RDF. . .

The motivation for doing so in e.g. Lisp, way back when, were for the
_computational_ properties which resulted, in terms of inexpensive
addition and the possibility of shared tails.

Indeed calling the resulting data structure 'lists' at all is a bit
misleading, as the fact that they are ordered is often of no interest.

'Sharable bag' would have been more accurate, but then McCarthy would
have had to call the language SheBangP or some such, which just
wouldn't have had the same impact :-).

ht
- -- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
    2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
            Fax: (44) 131 650-4587, e-mail: ht@inf.ed.ac.uk
                   URL: http://www.ltg.ed.ac.uk/~ht/
[mail really from me _always_ has this .sig -- mail without it is forged spam]
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Received on Tuesday, 20 February 2007 14:50:38 GMT

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