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Re: metadata subjects + 200 - a poll

From: Tim Berners-Lee <timbl@w3.org>
Date: Tue, 6 Apr 2010 23:12:52 -0400
Cc: AWWSW TF <public-awwsw@w3.org>
Message-Id: <7E4D43FB-6A07-42C3-889D-CF6D8DC9278F@w3.org>
To: Jonathan Rees <jar@creativecommons.org>
(2)  Bad Bob!

On 2010-03 -29, at 12:56, Jonathan Rees wrote:

> The below is similar to the question I sent recently(?) to Larry
> Masinter cc: www-tag and, I hope, sharpens some remarks I've made
> recently here. This story has nothing particularly to do with FRBR
> [2], I'm only using it as an example. All the same questions arise
> with any information-related ontology.
> Alice and Bob have a nice conversation about some particular FRBR
> expression, e.g. Moby Dick the original novel. They agree that they're
> talking about the same entity, they agree on its properties, and so
> on.
> Then they go their separate ways. Alice mints URI http://example.org/a
> meaning to use it as a name for the entity, and Bob mints URI
> http://example.org/b as a name for the same entity. If they knew about
> one another's actions, they would agree with the statement
> <http://example.org/a> owl:sameAs <http://example.org/b>.
> Now Alice arranges for some 200 responses to her URI, and Bob arranges
> some for his. Alice's responses have the property that they are very
> faithful to the entity. Each representation retrieved by GET
> http://example.org/a is FRBR manifestation of the expression. The
> expression and the Alice representations always have a lot in common -
> they say the same things, are about the same things, have the same
> paragraph and chapter structure, and so on. A representation has a
> passage on whale lice if and only if the expression does, and so on.
> Bob, meanwhile, arranges for 200 responses to http://example.org/b.
> These representations have a different character. Some of them are
> choice pages that link to online versions of the expression. Others
> are offers to sell copies (items) of the expression. Others are
> abridgements or adaptations (*different* expressions). Many of them
> have ads or "related resources" links on them - such as summaries of
> treatises on whale lice. Another is a table of contents that points to
> one file per chapter. So these representations do *not* have as much
> in common with the expression as the ones that Alice gives out.  They
> can be about things that the expression is not about (maybe whale
> lice), and they can fail to be about things that the expression is
> about (the topics discussed in text removed by abridgment).
> There is a very useful distinction to be made between the
> Alice-representations and the Bob-representations - e.g. for text
> mining.  As the two URIs supposedly name the same resource, the
> distinction is not captured as a difference in the properties of the
> named resource - one resource can't have different properties
> depending on how it's named.
> Possible resolutions:
> 1. The idea that the URI names the FRBR expression is silly. Get real,
> these are just web pages, not weird metaphysical constructions. So the
> special relationship of the nice Alice representations to
> <http://example.org/a> is easy to express - it's just a property of
> <http://example.org/a> that <http://example.org/b> doesn't have. If a
> URI is needed to refer to the FRBR expression, that URI has to be a #
> or 303 or something else.
> 2. Bob is doing something wrong ("bad practice"). If the served
> representations are so different from the thing named, either the
> representations [extra credit: which ones?] are wrong, or his URI
> isn't going to be taken to name what he thinks it names.

Yes. Naught Bob. <sameAs> is strong.

a) Others are abridgements or adaptations (*different* expressions).

Well, limite damage.  In fact this could be considered a benefit
if the abridged version is made as an accessability adaptation for
a reader with learning disablities, then it coudl be argued that this is a

b) Many of them have ads or "related resources" links on them - such as summaries of
treatises on whale lice. 

Limited damage, but some frustration. If commercial 
motivations drive the replacement of the representation Alice would give with one of these
then this becomes very dangerous if allowed.

c) Another is a table of contents that points to
one file per chapter.

Similar arguments to (a).  Note that this can be an automatic accommodation for mobile small-screen devices

d)  They can be about things that the expression is not about (maybe whale

Serious damage.

e)  and they can fail to be about things that the expression is

Serious damage.

> 3. No problem, the distinction between Alice's deployment and Bob's
> can be expressed as properties of the URIs (or rather of what the
> server(s) involved do with the two URIs), not the thing they name. We
> might postulate an entity what-an-HTTP-origin-does-with-a-URI that
> could be the possessor of the relevant properties (similar to Pat
> Hayes 'computational doppelganger' [1] I think):
>  [rdf:type awwsw:What-an-HTTP-origin-does-with-a-URI;
>   awwsw:origin-host-name "example.org";
>   awwsw:target-URI "http://example.org/a"^^xsd:anyURI ]
>  rdf:type awwsw:FRBR-well-behaved.

You can't use properties of the resources to distinguish between them
because they have agreed they are owl:sameAs and so all properties
of one apply to the other.

The doppleganger solution is frightful. 
And doppleganger fixups tend to go tripleganger before you know it.

What you can do of course is say

:moby a f:Work;
	f:expression  < http://example.org/a>; 
	foo:homePage   < http://example.org/b>.

Just avoid the owl:sameAs.

In some cases you could of usefully define a f:sameWork for two expressions of the same work. In fact please do.  
But not for an ad for the work and an expression of it, I suggest.

> 4. We entertain distinct modes of discourse in which the URIs are
> interpreted differently. In one mode we interpret the two URIs to be
> the single FRBR expression. In another mode we interpret the URIs to
> be distinct entities. (David's FTRR position?)

This is not Sem Web architecture, basically.

> 5. Suggest another  ______________________
> So here's the poll: Which of these do you like best?
> Just so you understand the consequences of your choice:
> 1. is a rejection of "information resource" and "URI ownership" i.e.
> of most of AWWW and parts of RFCs 2616 and 3986
> 2. is such a strong requirement that # URIs (or 303 or blank nodes)
> may be forced for many principled metadata subjects (similar to Alan
> Ruttenberg's position and maybe the ABLP theory)
> 3. forces tedious explanation of the relation of a resource to 200
> responses in any situation where someone might care; and is a
> rejection of the idea that a corresponds-to assertion is falsifiable,
> which is a premise of the httpRange-14 decision
> 4. rejects the 'semantic web' ideal that URI reference ought to be
> context-insensitive and that you ought to be able to integrate
> information coming from different sources in a straightfoward manner
> Jonathan
> [1] http://lists.w3.org/Archives/Public/public-semweb-lifesci/2007Oct/0059.html
> [2] http://archive.ifla.org/VII/s13/frbr/frbr.htm
> (p.s. I'm probably being sloppy in my application of FRBR; after all a
> FRBR manifestation of Moby Dick can have advertising in it, and thus
> be "about" whale lice even if the corresponding expression isn't. But
> hoping you get the idea.)
> I have no stake in any particular outcome, I just want a story that
> makes sense, and nothing does right now. Sorry if I'm being dense or
> fickle and thanks for staying with me. I hope I'm still bringing new
> material.
Received on Wednesday, 7 April 2010 03:13:00 UTC

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