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Re: How to avoid that collections "break" relationships

From: Peter F. Patel-Schneider <pfpschneider@gmail.com>
Date: Mon, 31 Mar 2014 08:41:11 -0700
Message-ID: <53398C97.2070604@gmail.com>
To: Ruben Verborgh <ruben.verborgh@ugent.be>
CC: Markus Lanthaler <markus.lanthaler@gmx.net>, Pat Hayes <phayes@ihmc.us>, public-hydra@w3.org, public-lod@w3.org, W3C Web Schemas Task Force <public-vocabs@w3.org>, Dan Brickley <danbri@danbri.org>

On 03/31/2014 08:29 AM, Ruben Verborgh wrote:
> Hi Peter,
>
> This is why I started by saying the focus of the discussion should be on what we want to achieve.
> With my proposed solution, it is achieved.
> Furthermore, this solution allows you to add any metadata you might like;
> a Hydra client just wouldn't need it (even though others might).
> Right now, don't need anything else than just finding the members of a collection.
>
>> But this is violating both the spirit and the letter of RDF.   It would be better to introduce entirely new syntactic mechanisms
> A new syntax would break everything that exists. How is that better?
> The proposed approach doesn't break anything and achieves what we need,
> without violating the RDF model.
>
>> Huh?  If you want to be in the RDF camp, you have to play by RDF rules.
> And we do that.
>
>     </people/markus> foaf:knows [ hydra:memberOf </people/markus/friends> ].
>
>      means “Markus knows somebody who is a member of collection X".

But that's not what this says.  It says that Markus knows some entity that is 
related by an unknown relationship to some unknown other entity.
>
> Check that collection X to find out if Markus knows more of them.
> I'm not saying there will be more in there… just saying that you could check it.
> Handy for a hypermedia client. Works in practice, doesn't break the model.
>
> If you want more semantics, just add them:
>      </people/markus/friends> :isACollectionOf [
>          :hasPredicate foaf:knows;
>          :hasSubject </people/Markus
>      ]
> But that is _not_ needed to achieve my 1 and 2.

Well this certainly adds more triples.  Whether it adds more meaning is a 
separate issue.


>
> Best,
>
> Ruben

It appears that you feel that adding significant new expressive power is 
somehow less of a change than adding new syntax.  I do not feel this way at all.


peter
Received on Monday, 31 March 2014 15:41:44 UTC

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