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Re: Last Call comments on RDFa Core

From: Harry Halpin <hhalpin@w3.org>
Date: Mon, 13 Dec 2010 11:19:24 -0000 (GMT)
Message-ID: <5b02829d5496e2274f66532dff17f790.squirrel@webmail-mit.w3.org>
To: "Toby Inkster" <tai@g5n.co.uk>
Cc: "Ivan Herman" <ivan@w3.org>, "Harry Halpin" <hhalpin@w3.org>, public-rdfa-wg@w3.org
> On Mon, 2010-12-13 at 10:49 +0100, Ivan Herman wrote:
>> I believe Toby's point is a little bit different. For all the reasons
>> you cite Facebook has decided to use a vocabulary whereby the objects
>> are all literals. That is their right, and they use RDFa consistently
>> in this sense.
>
> Yes, but further I was also trying to say that if I were designing a
> property like og:url I'd design it to take a literal value - not for
> pragmatic reasons, but because it makes sense.
>
> When you use a URI in the subject, predicate or object position of a
> triple, you're not really taking about the URI, you're talking about the
> resource identified by the URI. When you need to talk about the URI
> itself, and not the resource identified by it, you need to use a literal
> (or, to get around RDF's literal subject restriction, a blank node which
> is owl:sameAs the literal).
>
> <http://en.wikipedia.org/wiki/Use–mention_distinction> is a good
> explanation of the distinction. For a less dry take on it though, I'll
> call upon the late, great Charles Lutwidge Dodgson:
>

I am more than aware of de dicto and de re distinctions. For a long
explanation of why this preoptimizing around use/mention distinctions is a
bad idea, please read this paper by myself and Pat Hayes [1].

However in general that URIs are used to refer to and access resources. An
image URI or a webpage are really resources in the same way as magical
Semantic Web URIs that supposedly

To my knowledge, I have not seen a single halfway convincing usecase where
there is a reason why you would want to 'mention' a URI, i.e. refer to it
as a literal or xsd string.  If in general, you have a string of
characters that appear to be URI, you may want to use it - i.e. access it
using http - or refer to using RDF, whether or not it is the URI for Dan
Brickley himself or his webpage. Whether upon encountering a URI you use
it or refer to it with RDF should be in the hands of the end user, not
told to you by RDFa syntax.

If the entire reason for this premature optimization is based on a
distinctly idiosyncratic metaphysics...a distinction that TimBL has agreed
can not in general be coherently explained...then I see no reason why the
RDFa WG should punish end users in order to maintain this distinction by
making them choose different @attributes based on this distinction.

As it is also particularly seems self evident that endusers already have
trouble understanding any supposed distinctions here and are already using
URIs where literals should be and vice versa anyways. So pave the cowpaths
here rather than upholding a likely faulty understanding of philosophy of
language.

[1]
http://www.ibiblio.org/hhalpin/homepage/publications/indefenseofambiguity.html

>         Alice was walking beside the White Knight in Looking Glass Land.
>         	"You are sad." the Knight said in an anxious tone: "let me sing
>         you a song to comfort you."
>         	"Is it very long?" Alice asked, for she had heard a good deal
>         of poetry that day.
>         	"It's long." said the Knight, "but it's very, very beautiful.
>         Everybody that hears me sing it - either it brings tears to
>         their eyes, or else -"
>         	"Or else what?" said Alice, for the Knight had made a sudden
>         pause.
>         	"Or else it doesn't, you know. The name of the song is called
>         'Haddocks' Eyes.'"
>         	"Oh, that's the name of the song, is it?" Alice said, trying to
>         feel interested.
>         	"No, you don't understand," the Knight said, looking a little
>         vexed. "That's what the name is called. The name really is 'The
>         Aged, Aged Man.'"
>         	"Then I ought to have said 'That's what the song is called'?"
>         Alice corrected herself.
>         	"No you oughtn't: that's another thing. The song is called
>         'Ways and Means' but that's only what it's called, you know!"
>         	"Well, what is the song then?" said Alice, who was by this time
>         completely bewildered.
>         	"I was coming to that," the Knight said. "The song really is
>         'A-sitting On a Gate': and the tune's my own invention."
>
> --
> Toby A Inkster
> <mailto:mail@tobyinkster.co.uk>
> <http://tobyinkster.co.uk>
>
>
Received on Monday, 13 December 2010 11:19:26 UTC

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