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Re: Semantics of 301 [was Re: More comments on draft report]

From: Dan Connolly <connolly@w3.org>
Date: Wed, 17 Feb 2010 17:19:31 -0600
To: Jonathan Rees <jar@creativecommons.org>
Cc: David Booth <david@dbooth.org>, AWWSW TF <public-awwsw@w3.org>
Message-ID: <1266448771.7402.129.camel@pav.lan>
On Wed, 2010-02-17 at 13:29 -0500, Jonathan Rees wrote:
[...]
> Maybe if you could show what RDF graph you would curate in the case of
> domain name sale or a 301 that changes different(U,V) from false to
> true that would help. (I don't understand how you would ever deduce
> that occurrences of a URI in two exchanges could be converted into the
> same URI in the graph.) But I would prefer to just say this
> complication of extracting meaningful information from a situation
> that is on the surface inconsistent is out of scope. The problem is
> hard enough already.

Jonathan, are you familiar with context logic, lifting and all that?

  Contexts: A Formalization and Some Applications
  http://www-formal.stanford.edu/guha/guha-thesis.ps 

(my larch notes: http://www.w3.org/XML/9711theory/ContextLogic.lsl )

(a pretty good hypertext document about it:
  http://www.cyc.com/cycdoc/vocab/context-vocab.html )

I sometimes think of HTTP messages as contexts in that sense.

There are 2 extremes:
  (1) all HTTP replies are in the same context, and every message
  from each rational party should be consistent.

  (2) each HTTP message is its own context; you can't really
  tell whether a URI in one message is to be interpreted in
  the same way as that URI in another message unless you have
  some really good reason to.

This is one of those things where people are really good at
figuring it out and machines need a lot of help. e.g. if
I ask you "Have you seen Bob?" you intuit that I don't
mean "Have you ever seen Bob in your lifetime?" nor
"Have you seen Bob in the last microsecond?" but rather
something like "In the domain of discourse where today
is all the time there is, Have you seen Bob?"

I think it might be useful to infer that if 2 messages
are causally related (e.g. you followed a link or a redirect
from one to the other), then they can be interpreted
in the same context... or something like that. I've
never really nailed it down.



-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
gpg D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Wednesday, 17 February 2010 23:19:34 GMT

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