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Re: firts and rdf:rest as functional property

From: Reto Bachmann-Gmür <reto.bachmann@trialox.org>
Date: Fri, 20 Mar 2009 17:32:58 +0100
Message-ID: <49C3C53A.5030102@trialox.org>
To: Michael Schneider <schneid@fzi.de>
CC: Semantic Web <semantic-web@w3.org>, Bijan Parsia <bparsia@cs.man.ac.uk>
With analogous argument you could conclude that a foaf:Person isn't a
person. But what do we want more than descriptions of persons list and
tbox statements that allow as to exclude that some resources do describe
a list or a person. We can never have enough statements to be able to
logically exclude any resource that isn't a list from being a list.

As for your examples I see no problem with 1 and 3:
- 1 describes a part of list (we know there is at least one list
containing A, B and C in this order)
- 3 describes three lists ({A1,B}, {A2,B} and {B})

The example 2 violates what's the convention described by RDF semantics,
however I see no way to add tbox statements with the (current)
expressivitiy of OWL that would contradict this graph.

Cheers,
Reto

Michael Schneider said the following on 03/20/2009 04:53 PM:
> (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)
> Tel  : +49-721-9654-726
> Fax  : +49-721-9654-727
> Email: michael.schneider@fzi.de
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>   
Received on Friday, 20 March 2009 16:33:52 GMT

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