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Re: rev and the costs of inverses/aliases in SPARQL

From: Stephane Corlosquet <scorlosquet@gmail.com>
Date: Mon, 8 Mar 2010 11:58:01 -0500
Message-ID: <1452bf811003080858r304d27j1a41769f1d676b59@mail.gmail.com>
To: Dan Connolly <connolly@w3.org>
Cc: public-sparql-dev <public-sparql-dev@w3.org>, public-rdfa <public-rdfa@w3.org>
>
> Does anyone have 1st-hand experience to share?
>

Drupal 7 uses @rev to associate a taxonomy term to the vocabulary it belongs
to using rev="skos:member". I could not find an inverse property for
skos:member so rev is very handy. Drupal stores the vid (vocabulary id) for
each term, and the inverse relationship (vocabulary to term) does not exist
explicitly, and that's what skos:member naturally maps to.

Steph.

On Mon, Mar 8, 2010 at 10:00 AM, Dan Connolly <connolly@w3.org> wrote:

> I just ran into this message again from an HTML 5 validator:
>
> "The rev attribute on the a element is obsolete. Use the rel attribute
> instead, with a term having the opposite meaning."
>
> This seems to encourage the pattern of minting an inverse
> for each property, a la:
>
>  abridgement
>  abridgementOf
>  -- http://vocab.org/frbr/core.html
>
> Doesn't that just gum up the works when doing SPARQL queries? Which
> do you query for, abridgement or abridgementOf? Or do you use
> a UNION?
>
> It's one thing to discover, post-hoc, that two properties are
> inverses of each other, and to write down that relationship.
> But to make up these inverse-aliases by choice seems like
> a big waste, to me.
> (see also http://esw.w3.org/topic/HasPropertyOf bit on inverses and
> aliases)
>
> How are SPARQL users dealing with this in practice?
>
>
> Meanwhile, RDF/XML doesn't have syntax for inverting a relationship
> (a la is/of in N3), and there's data that says rev="..." is
> too confusing for HTML authors to use.
>
> "The short answer is unfortunately "NO". Use of "rev" SHOULD be
> avoided."
>  -- http://microformats.org/wiki/rel-faq
> "the only <link rev=""> link to appear is rev="made" (to point to the
> author's page)  and the latter is not used that much more than the more
> sensible rel="author". Also, ironically, just off the graph in position
> 21 is rel="made", probably showing that the distinction between rel and
> rev may be too subtle for many authors."
>  -- http://code.google.com/webstats/2005-12/linkrels.html
>
>
> Would the RDFa authoring community miss a/@rev if it went away?
> Does anyone have 1st-hand experience to share?
>
>
> --
> Dan Connolly, W3C http://www.w3.org/People/Connolly/
> gpg D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
>
>
>
>
>
Received on Monday, 8 March 2010 17:00:28 GMT

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