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Re: Problem definition

From: Jonathan Rees <jar@creativecommons.org>
Date: Mon, 21 Feb 2011 12:57:00 -0500
Message-ID: <AANLkTin1eQrFaWcVzB0wcdNTAFidxXx6Eg9Bo82cizmC@mail.gmail.com>
To: nathan@webr3.org
Cc: AWWSW TF <public-awwsw@w3.org>
On Thu, Feb 17, 2011 at 2:32 PM, Nathan <nathan@webr3.org> wrote:
> resend (sent from wrong address previously)
>
> Hi,
>
> Tried to write up the problem, as I see it (keeping away from solutions
> at the minute).
>
> Agree with the following summary(?):
>
> Competing uses of dereferenceable absolute http scheme URIs:
>
> 1: network accessible resource
>   - uri as an address for some process on the web
> 2: representation
>   - uri as referring to a specific content+content-meta
>     (fixed resource/simple IR)
> 3: document / "source of information"
>   - not well defined, typically "web of documents"
> 4: primary topic of a document / "source of information"
>   - when a document is primarily about one thing
> 5: any thing
>   - any single thing, whatever a name is commonly used to refer to
>
> Ideal Layers of the Web:
>
>                           _ network accessible resources
>  Network / Computers ----|_
>         |                   representations
>    [hidden by]
>         |                 _ sources of information
>   Web of Documents ------|_
>         |                   documents
>    [hidden by]
>         |                 _ primary topic of a document
>    Web Of Data ----------|_
>                             any thing

Don't know what you mean by 'web of data'.  What are its nodes and
links, such that it
is not 1-1 with a subset of the 'web of documents'?  What are the
properties of the 'web of data'?

Also, do you think that every document (w.g. a .wav file, or an empty
file) has a primary topic? If so I would prefer not agree with you.

> Proof of each URI use:
>
> 1: network accessible resource
>   <link rel="pingback" href="/pinger" />
>   (treats @href like an address)

ok

> 2: representation
>   in a document you GET from <u>
>   <link rel="stylesheet" href="/styles.css" />
>   creates triple <u> xhv:stylesheet "<u>/styles.css" in RDFa
>   (uses <u> to identify representation)

How do you know that <u> is used that way? I would have said this is
the same as case 1 - the address from which to fetch the style sheet
(if not cached). The URI, if it 'identifies' a representation,
certainly might 'identify' different ones in different circumstances,
and that's OK.

> 3: document / "source of information"
>   <a href="/foo.html">foo</a>

Again, not sure how different from 1 and 2

> 4: primary topic
>   <meta property="og:title" content="blog post title" />

Tell me more about this? You're referring to whatever the curie
og:title turns into, yes? Or are you referring to the base URI
referring to the primary topic of...?  I don't get this.

> 5: any thing
>   have you met <a href="<u>">my mum</a> ?
>   <http://xmlns.com/foaf/0.1/name>

To say that the URI refers to a mum in this case is something I would
have to be convinced of.
I do appreciate that in English ones puts a URI in a referring context
and often means the primary subject, but I am not convinced anyone has
this in mind for @href.

So, willing to be convinced, but this example as written doesn't do it for me.

> chimera theory:
>
>  "URI refers to a 'chimera' entity that has some of the properties of
>   the page and some of the properties of either its primary topic or
>   the entity named on the page by the URI."
>
> is chimera theory current reality? yes
>  many pages, like a doc with open graph, uses the same URI to refer to:
>   - network accessible document
>   - representation
>   - document
>   - primary topic
>   - any thing (usually also the primary topic "blog post" or "my mum")

Examples would be enormously helpful.  I think the *intent* is
probably that in each case (each occurrence of the URI) the URI is
only meant to one of these things at a time. RDF semantics - the
desire for a model - is the only thing that forces the existence of
the 'chimera'. A chimera intent might be forced, but it would be
difficult, and probably wouldn't be done consciously.

> problem:
> web of data / sem web requires one name to be used to refer to one thing.
>
> httpRange-14:
> there exists a class of information resources, and dereferencable http
> scheme URIs are used to refer to these
>
> httpRange-14 problem, the rel cc:license problem:
> "information resource" is loosely defined, such that when a GET pulls
> back HTML which contains a "blog post", things from all three layers are
> classed as an information resource
>  - representation
>  - the document
>  - primary topic, the blog post.
> does dc:created refer to representation, to the document, or the blog
> post? does cc:license apply to the representation, the document or the
> blog post?

I don't agree that 'information resource' being loosely defined is the
source of the problem; the problem is a failure to say (1) *which*
information resource and (2) what 'is a representation of' means. I've
attempted to rectify this in my axioms document and would bet $5 I
could get the current TAG to agree with it.

> does httpRange-14 resolution remove chimera state of the web?
>  no.

Its elaboration in the form of Tim's posts on information resources
does. You could argue that these posts are not normative, but then
neither is the TAG's resolution. But if you try to 'game' the
resolution by quibbling over what an information resource is, which
one is meant, and what constitutes representation, the discussion is
pretty much over.

> potential next steps:
>  - remove chimera state from web of data
>    (possible B.C. breaks)
>  - live with chimera state and focus on disambiguation
>    (requires interpretation of statements, only graphs can be
> interpreted to the level required to disambiguate chimera state)

Looking forward to it.

It should be possible to come up with contradictions induced by the
chimera interpretation; this is on my to-do list. But to get a
contradiction you need inference, and it seems to me that the people
who dislike httpRange-14 are the same as the ones who don't care about
inference. That's actually good news since if so it will alway be
possible to interpret toucan-document URIs as referring either to
toucans or to documents (or to chimeras). That might make everyone
happy.

We need to look more closely at interoperability scenarios. One
solution is to just live without a shared interpretation. (That's what
happens if you withdraw the resolution and don't replace it with
something else.) We have to find out at what cost.

> Best,
>
> Nathan
>
Received on Monday, 21 February 2011 17:57:35 GMT

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