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Re: Towards a final consensus re statements & statings

From: Graham Klyne <GK@Dial.pipex.com>
Date: Mon, 11 Dec 2000 00:00:26 +0000
Message-Id: <>
To: Pierre-Antoine CHAMPIN <champin@bat710.univ-lyon1.fr>
Cc: www-rdf-interest@w3c.org
At 04:18 PM 12/8/00 +0100, Pierre-Antoine CHAMPIN wrote:
>  1.  the notion of stating is a useful notion, and M&S does not mention 
> it at all, like the authors have "forgotten" it. Since the concepts of 
> reified statement/stating are quite near, it is easy to interpret that 
> the authors... would have written "stating" if they had made the 
> distinction in the first place.
>  2.  it is very easy to write a piece of RDF with two reified statements 
> being identical, and M&S does *not* make it illegal. Since a statement is 
> unique, it looks like a bug in the model, unless reified statements are 
> in fact statings.
>  3.  the example for reification (namely "Ralph says that Ora was the 
> creator of the page") tastes just like a stating. One would like to add 
> the date when Ralph said that, hence the problem raised by Jonas 
> Liljegren : if I also want to state that "Pierre-Antoine said that Ora 
> was the creator of the page, at another date", then which date applies to 
> which stater ?
>   st1: [Ora, creator, page]
>   st2: [st1, saidBy, Ralph]
>   st3: [st1, saidAt, 01/12/99]
>   st4: [st1, saidBy, Pierre-Antoine]
>   st5: [st1, saidAt, 01/12/00]
>Those are the main reasons I had to think that reified statements were in 
>fact statings.
>Now, here are critics for each argument, who lead me to think maybe I was 
>wrong :
>  about 1.  That argument is not the stronger one... Actually, I would 
> rather stick to the spec as long as I can... So, what about 2. and 3. ? :)

I agree about sticking to the spec where it is adequate to the purose 

>  about 2.  It is actually very easy to write a piece of RDF where any 
> resource is duplicated, not only statements. And it is not considered a 
> bug... although we might have troubles handling it ! Example :
>   <rdf:Description about="http://www.w3.org/">
>     <as:contentQuality> Excellent </as:contentQuality>
>   </rdf:Description>
>   <rdf:Description about="urn:WWWConsortium">
>     <as:homepage>
>       <rdf:Description id="localID"/>
>     </as:homepage>
>   </rdf:Description>
>   <rdf:Descritpion about="mypage.html">
>     <as:pointsTo rdf:resource="#localID"/>
>   </rdf:Description>
>where #localID and http://www.w3.org/ are in fact the same thing.

Maybe I'm dense here, but I don't see the problem.

>   about 3.  I already submitted the idea below on the list, but I will go 
> further : the problem raised by Jonas is not a problem ! If we do 
> consider that the reified statement is really a statement rather than a 
> stating, then the date should not be a property of st1, but rather of st2 
> and st4 !
>   st1: [Ora, creator, page]
>   st2: [st1, saidBy, Ralph]
>   st3: [st2, at, 01/12/99]
>   st4: [st1, saidBy, Pierre-Antoine]
>   st5: [st4, at, 01/12/00]
>The statements st2 and st4 are actually statings, not because *every* 
>reified statement be a stating, but because of the particular meaning of 
>their predicate "saidBy".

Yes, I agree.


Graham Klyne
Received on Monday, 11 December 2000 21:24:36 UTC

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