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Re: firts and rdf:rest as functional property

From: Story Henry <henry.story@bblfish.net>
Date: Fri, 20 Mar 2009 17:13:03 +0100
Cc: Reto Bachmann-Gmür <reto.bachmann@trialox.org>, "Semantic Web" <semantic-web@w3.org>, "Bijan Parsia" <bparsia@cs.man.ac.uk>
Message-Id: <C75824AA-0340-4B4A-A372-F07B6BD9695E@bblfish.net>
To: "Michael Schneider" <schneid@fzi.de>

On 20 Mar 2009, at 16:53, Michael Schneider wrote:

> (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?

Ok. So I understand. If in N3 you write a list, you have to open and  
end it with
( and ) respectively. So it will always be complete. If you write it  
with rdf:first, rdf:last,
then you are in the undefined territory described below:

>
> (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

Well this is ok I think. You just have two lists here A1 and A2. One  
can do stuff
Like this in Java quite easily, and it would not be a bad thing, as  
you would use less
memory.



>
>
> 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)
> Tel  : +49-721-9654-726
> Fax  : +49-721-9654-727
> Email: michael.schneider@fzi.de
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> = 
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Received on Friday, 20 March 2009 16:13:57 GMT

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