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Re: adding several values to the same predicate == Bag??

From: Richard Newman <r.newman@reading.ac.uk>
Date: Thu, 14 Sep 2006 21:02:47 -0700
Message-Id: <FFF4D03C-ADCA-40B1-8305-9CE8C279FE61@reading.ac.uk>
Cc: semantic-web@w3.org
To: "Aldo Bucchi" <aldo.bucchi@gmail.com>

Not quite. In ntriples:

graphA:
<http://www.recshop.fake/cd/Beatles> cd:artist "John" .

graphB:
<http://www.recshop.fake/cd/Beatles> cd:artist "Paul" .

graphC:
<http://www.recshop.fake/cd/Beatles> cd:artist _:x
_:x rdf:type rdf:Bag .
_:x rdf:_1 "John" .
_:x rdf:_2 "Paul" .


Whether you consider graphC to be equivalent to graphA U graphB is  
another matter. The model theory won't support you if you do, though:

"There is no assumption that a property of a container applies to any  
of the elements of the container, or vice versa."[1]

So, when would you use a container? Well... I don't use them very  
often. The only one I can think of offhand is a committee; the  
committee is a bag of its members, and the committee can author  
documents. The individual members do not necessarily author a  
document; the committee does. You might say:

<http://www.recshop.fake/cd/Beatles> cd:artist ex:theBeatles .
ex:theBeatles a rdf:Bag , ex:Band ;
               rdf:_1 "John" ;
               rdf:_2 "Paul" ;
               rdf:_3 "Ringo" ;   # Remember, it's unordered! ;)
               rdf:_4 "George" .


-R


[1] <http://www.w3.org/TR/rdf-mt/#Containers>


On  14 Sep 2006, at 8:41 PM, Aldo Bucchi wrote:

>
> Hi all,
>
> This is a very very simple question... but I am trying to interiorize
> myself with containers...
>
> having:
>
> graphA =
> <rdf:Description
> rdf:about="http://www.recshop.fake/cd/Beatles">
> <cd:artist>John</cd:artist>
> </rdf:Description>
>
>
> graphB =
> <rdf:Description
> rdf:about="http://www.recshop.fake/cd/Beatles">
> <cd:artist>Paul</cd:artist>
> </rdf:Description>
>
>
> graphC =
> <rdf:Description
> rdf:about="http://www.recshop.fake/cd/Beatles">
> <cd:artist>
>   <rdf:Bag>
>     <rdf:li>John</rdf:li>
>     <rdf:li>Paul</rdf:li>
>   </rdf:Bag>
>  </cd:artist>
> </rdf:Description>
>
>
> does the following hold true?
>
> graphA U graphB = graphC
>
>
> Can anyone point to advanced material on containers and collections??
>
> Thanks,
> Aldo
>
> -- 
> ::::: Aldo Bucchi :::::
> mobile (56) 8 429 8300
>
Received on Friday, 15 September 2006 04:02:59 UTC

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