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RE: firts and rdf:rest as functional property

From: Michael Schneider <schneid@fzi.de>
Date: Fri, 20 Mar 2009 16:53:49 +0100
Message-ID: <0EF30CAA69519C4CB91D01481AEA06A0011D9AEB@judith.fzi.de>
To: Reto Bachmann-Gmür <reto.bachmann@trialox.org>
Cc: "Semantic Web" <semantic-web@w3.org>, "Bijan Parsia" <bparsia@cs.man.ac.uk>
(I hope, my ASCII art will survive...)

>-----Original Message-----
>From: semantic-web-request@w3.org [mailto:semantic-web-request@w3.org]
>On Behalf Of Reto Bachmann-Gmür

>Is it just the absence of explicit cardinality and functionality
>statement that makes it an non-real list for you? How would in your
>opinion a proper list be designed?


(1) Lists should terminate, but there is no enforcement of a final rdf:nil:

      A -> B -> C   // no NIL 

(2) Lists should not be cyclic, though this is possible with RDF lists:

      A -> B
      ^    |
      |    v
      D <- C

(3) Lists should not have more than one head, but it's possible with RDF
lists:

      A1
       \
        v
         B -> rdf:nil
        ^
       /
      A2
        
Functionality and min-1 cardinality would not help here. 

(In (1), the list could be terminated by anything else but rdf:nil, so the
min-1 axiom would be satisfied for rdf:rest).

>Cheers,
>reto

Cheers,
Michael

--
Dipl.-Inform. Michael Schneider
Research Scientist, Dept. Information Process Engineering (IPE)
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Email: michael.schneider@fzi.de
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Received on Friday, 20 March 2009 15:54:30 GMT

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