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Re: How to avoid that collections "break" relationships

From: Ruben Verborgh <ruben.verborgh@ugent.be>
Date: Mon, 31 Mar 2014 17:29:06 +0200
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>
Message-Id: <ADF7C346-B2CA-4B7A-A35A-CB4513EFB6D0@ugent.be>
To: "Peter F. Patel-Schneider" <pfpschneider@gmail.com>
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".

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.

Best,

Ruben
Received on Monday, 31 March 2014 15:29:40 UTC

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