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RE: Some TAG review of "Cool URIs for the Semantic Web"

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 5 Oct 2007 09:35:11 -0500
Message-Id: <p06230905c32bf29d0bca@[192.168.1.2]>
To: "Marc de Graauw" <marc@marcdegraauw.com>
Cc: "'Booth, David \(HP Software - Boston\)'" <dbooth@hp.com>, "'Technical Architecture Group WG'" <www-tag@w3.org>

>David Booth:
>
>| > From: Pat Hayes
>| > [ . . . ] I'd prefer to say that what makes
>| > something an 'information resource' is not how it can be
>| > xx:represented - which is a can of worms - but just that it is the
>| > kind of thing that emits 200 codes alongside bitstrings
>| (which we can
>| > call 'representations' if you like . . . )
>|
>| A big +1 from me, of course.  Whether it can emit 200
>| reponses with "representations" is all that is relevant to
>| Web architecture.
>
>This raises a question for me. Suppose I have no clue about 
>webdesign, and serve
>a picture of me from:
>
>http://www.marcdegraauw.com/file001/
>
>1 October 2007 I change my mind, and serve my CV from
>
>http://www.marcdegraauw.com/file001/
>
>and the picture from
>
>http://www.marcdegraauw.com/file002/
>
>What would you now say:
>
>[1] http://www.marcdegraauw.com/file001/ is an IR which denoted Marc's picture
>before 1 October 2007 and Marc's CV after 1 October 2007.

Better, which denoted a thingie which looked (?) like the picture 
until then and the CV after then. The problem with this isn't the URI 
or the denotation, but the fact that this is a very odd thingie. Its 
naughty to create such thingies, they confuse people and resist 
normal classification. But consider
http://www.washingtonpost.com/wp-dyn/content/technology/index.html?wpisrc=newsletter
which gets me something different every day. We don't have a problem 
with that, yet its always "changing". Its OK because we have a 
category for this kind of changing thing, its a 'daily column', and 
we know about those and can work with them. Similarly for webcams and 
so on. But pictures that morph into CVs aren't in our conceptual 
space, so they bother us. When I moved from England to upstate NY I 
had a hard time at first with things that went back and forth between 
a clock and a thermometer, but you get used to them eventually.

>Or:
>
>[2] Marc, you have no clue about web design, you served a different IR before
>and after 1 October 2007, go read Tim Bernes-Lee's "Cool URI's don't 
>change" [3]
>and mend your ways.

I don't think this is really to do with Web architecture as such. The 
problem arises here because Web technology makes it so easy to create 
new 'kinds' of document-like things that behave in all sorts of 
irrational ways, like images that change into text for no reason.

>I always assumed IR was intended as a sort of refined notion of "document" in
>[3], and I would thus say [2]. Webarch suggests as much.

What REST says is, an IR is a function from times to representations. 
Of course that allows for either answer, but it sure allows [1]. I 
think that in order to get to the intuition that justifies [2], you 
have to ask, "representation of what?" and ask if that is the kind of 
thing that should be represented.

BTW, philosophers have been here. There is a famous example by 
Goodman called grue/bleen. Grue means: green up to 1 October 2007, 
then blue. Bleen is the opposite. Question: are these colors as good 
as green and blue? Seems obvious they are not. But we can't base this 
intuition on the form of the definition, because if we had been 
brought up to like grue/bleen, then green is defined as: grue up to 1 
October 2007, then bleen; and similarly for blue. So as far as 
definitions are concerned, there is perfect symmetry here. So if my 
lawn suddenly turns blue, what justification do I have for saying 
that it changed color? It was just a grue lawn all the time.

>
>I think saying [1] may be coherent, but then we still need some notion of
>"concept" to replace "IR" in [2].

AArgh, don't go there. This is taking the entire bottom off the can 
of worms. At the very least, call them something like 'documents'.

>Computers can't do much with it, but for
>people it is often extremely easy to distinguish them, and sentences 
>such as [2]
>are pretty essential to (improving) the Web.

<aside>
I wonder, does the Web really need improving in this regard? Does it 
even make sense to try coining URIs that will last for 2000 years? 
Given the results I often get from Google, seems to me that part of 
the problem with the current Web is that many URIs last TOO long. The 
Web is cluttered with instantly-accessible information that is now 
outdated and often false (people's old addresses, old blogs that are 
archived, etc..). Might be better to allow quite a lot of URIs to 
just die quietly, unremembered and unmourned. Let the second law of 
thermodynamics do its gentle work here, as in the rest of the 
universe. It takes less energy, anyway.
</aside>

Pat

>
>Marc de Graauw
>
>http://www.marcdegraauw.com
>
>[3] http://www.w3.org/Provider/Style/URI


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Received on Friday, 5 October 2007 14:35:33 UTC

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