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Requirements for Any Theory of "Information Resource"

From: David Booth <david@dbooth.org>
Date: Mon, 28 Feb 2011 14:36:15 -0500
To: AWWSW TF <public-awwsw@w3.org>
Message-ID: <1298921775.2525.8507.camel@dbooth-laptop>
I thought I would take this opportunity to provide some feedback on
Jonathan's draft: Requirements for Any Theory of "Information Resource".

1. Regarding:
The challenges to explaining "information resource" are: (1) to make
"information resources" logically independent of Web dereference (and in
particular the HTTP protocol), while saying rigorously what it means for
one of them to be "on the web" at a given URI
Perhaps define an abstract "AGET", which is implemented as GET in the
HTTP protocol, and in other ways by other protocols.

2. Regarding:
The main contribution of this note is to say that the properties of an
information resource are those that are invariant over its
That sounds pretty good.  But isn't something like that true of *all*
resources?  As in "the properties of a resource are those that are
always true of that resource"?  BTW, those invariants are the assertions
that should be included in the URI's declaration.

3. Regarding:
'Has reading' is not functional, because we want to admit
interpretations where readings vary by media type, language, session,
time, whim, etc.
But you could make 'has reading' functional: just include time and
request as arguments, as in ftrr:InformationResource
Or you could let the request be broken apart into multiple variables.

If we consider a set of variables v1..vn under which 'has reading'
becomes functional: f(v1, ... vn), then when you talk about metadata
Let P be a metadata property, let R be an 'information resource', and
let x be a member of the range of P. Then P(R,x) if and only if P(S,x)
holds for all readings S of R.
I wonder if there would be a way to 

I like the general direction you're going in, when you talk about
metadata properties:
Let P be a metadata property, let R be an 'information resource', and
let x be a member of the range of P. Then P(R,x) if and only if P(S,x)
holds for all readings S of R.
However, I'm not certain of the "only if" direction.  The "only if"
direction seems to be saying that R cannot have any property that is not
observable through some S.  Maybe that's correct -- I'm not sure.  It
reminds me of the discussion of intensional versus extensional semantics
in RDF

If you think of R as a function f of a set of n variables v1..vn: 
f(v1, ... vn), and c1 is a constant and f1 is a derived function of n-1
variables v2..vn such that:

  f1(v2, ... vn) = f(c1, v2 ... vn)

then it makes sense to try to relate properties that hold of f to
properties that hold of f1, but how?  Perhaps it can be done if we
restrict those properties to ones whose truth is determined solely by
the observable values of f(v1, ... vn):

  MP is the set of properties with domain 'information resource' 
  such that for any P in MP and any information resource f, there 
  is a corresponding property ("little-p") p, such that: P(f) iff
  p(f(v1, ... vn)) for all values of v1..vn.

Maybe something like this is what you're getting at?

4. I like this idea:
The IR must 'fess up' to things that all of its readings do. This rules
out pathologies where something is P-related to all of a document's
translations but not to the IR itself. The practical benefit is that it
lets you 'gamble' on hypotheses of an IR formed by investigating a
number of its readings. You're not guaranteed to be right, but you may
be willing to act on the hypothesis.

5. Regarding:
(def) An 'information resource' is 'bound to' a URI iff every simple IR
that is 'authorized for' the URI 'is a reading of' the information

This formalizes "on the web".

I think that's a pretty good definition of something, but I'm not sure
it formalizes the notion of an information resource being "on the web",
since that definition only talks about the binding between a URI and an
information resource.  Usually when something is "on the web", there are
representations available via GET.

But maybe you're using the word "binding" different than I expect.  I
think of a binding as an association between the URI and the information
resource, just as an "interpretation" in RDF semantics maps URIs to

6. Regarding:
(candidate) For any set {S1, S2, ...} of 'simple IRs' there exists an IR
that has S1, S2, ..., as readings, and no others.
This seems pretty reasonable, if we interpret "there exists" to mean "in
theory there could exist".

7. Regarding:
(def) An interpretation of an RDF graph 'respects IR bindings' if, for
each dereferenceable URI occurring in the graph (outside of literals),
the URI is interpreted to be an IR bound to that URI. 

Nice!  I think the wording will have to be tightened up slightly, but I
think the idea is very good.

8. Regarding:
A satisfying interpretation 'respects IR bindings' if it is also
satisfying for the graph formed by merging (a) the given graph, (b) a
set of 'binding statements', one per dereferenceable URI occurring in
the graph,

Yes!  Item (b) corresponds to step 1.a in the process for determining
resource identity that I proposed at the Semantic Technology Conference
last year

9. Regarding:
and (c) an appropriate RDF axiom set derived from the above axioms. The
'binding statement' for a URI uuu is defined here to be the statement
<uuu> :boundTo "uuu"^^xsd:anyURI.

Yes!  That is exactly what my proposed n3 rules for an HTTP 200 response
150. # httpRange-14 rule: 200 response => InformationResource
151. # http://lists.w3.org/Archives/Public/www-tag/2005Jun/0039.html
152. {       ?r uri:hasURI ?u .
153. 	?u http:hasGetReply ?reply .
154. 	?reply http:hasStatusCode 200 .
155. 	# ...
156. } => {					
157. 	?r a awww:InformationResource .
158. 	# ...
159. 	} .

FYI, your :boundTo property corresponds to the log:uri property defined
by TimBl
and the :hasUri property that I defined at line 95:

10. In this statement:

  [:isBoundTo "<http://example/z>"^^xsd:anyURI]

Don't you have extra angle brackets around that URI?  Shouldn't it be:

  [:isBoundTo "http://example/z"^^xsd:anyURI]

11. One thing that isn't mentioned, and may not need to be addressed in
this document, but needs to be addressed somehow/somewhere: In reality,
URI-resource bindings change (slowly) over time, when domain names are
sold or web sites are reorganized. 

David Booth, Ph.D.

Opinions expressed herein are those of the author and do not necessarily
reflect those of his employer.
Received on Monday, 28 February 2011 19:36:44 UTC

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