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Re: Well Behaved RDF - Taming Blank Nodes, etc.

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Wed, 19 Dec 2012 09:45:50 -0500
Message-ID: <50D1D31E.9020000@thefigtrees.net>
To: Atila <atilaromero@gmail.com>
CC: Semantic Web <semantic-web@w3.org>
On 12/19/2012 7:53 AM, Atila wrote:
> On 18-12-2012 15:11, Lee Feigenbaum wrote:
>> For the latter, I'd probably just model it as :Jane :wants :Apple or 
>> something like that.
> Hum, and if she wants a green apple, like
>
> :Jane :wants [a :Apple; :color :Green]
>
> ?

Well, if my intuition is right that

:Jane :wants [a :Apple]

is incorrect modeling for "Janes (notionally) wants an apple", then the 
above is similarly incorrect for Jane (notionally) wanting a green 
apple, and instead I'd suggest:

:Jane :wants :GreenApple .
:GreenApple rdfs:subClassOf :Apple ; rdfs:subClassOf [ a owl:Restriction 
; owl:onProperty :color ; owl:hasValue :Green ] .

(oh look, a blank node! :-) )

> I think that the botton line is that machines doesn't need blank nodes 
> at all, they can work very well without it. But humans do.
> It is possible to express things using URIs to everthing, but it is 
> just too messy in some cases. It would be painful, specially to 
> beginners.

Blank nodes are subtle and non-obvious (see the above discussion). I 
disagree that they're simpler for beginners. I think beginners would 
have an easier way getting started without them.

> When i first heard about RDF, I got scared that every single thing 
> would got to have an URI. I thought "that can describe social networks 
> well, but will be useless to NLP", then I heard about blank nodes and 
> saw I was wrong.
>

We do NLP all the time and everything gets a URI.

Lee
Received on Wednesday, 19 December 2012 14:46:15 UTC

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