This is part of A Model of Authority in the Web.

Indirection needs Redirection

Questions about levels of indirection show up in designs layered on HTTP; for example:

Let's explore an example somewhat analagous to the second question, analyzed with ABLP logic.

Suppose Bob signed a manifesto in 1995:

[] a cyc:AffixingSignature; cyc:performer Bob;
   cyc:objectActedOn <>.

Time passed and the organization no longer stood by the manifesto, though it was widely cited, e.g. by a 2008 article published by Penguin House:

  cyc:publicationDate_IBO "2008-05-16"^xsd:date .

The organization replaced the manifesto file on the server with some metadata about the manifesto, without adding any sort of redirect. A request came in to the origin server and was handled normally:

C1 ht:connectionAuthority "";
   ht:requests (Q1).

Q1 ht:absoluteURI "";
  ht:methodName "GET";
  ht:resp A1.

A1 ht:statusCodeNumber "200";
  hs:messageEntity {
    <> dc:creator Bob.

      dc:source <>.

Meanwhile, Bob actually died in 2006:

Bob cyc:dateOfDeath "2006-01-23"^xsd:date.

Among the things that now says is that the 2008 article cites the manifesto. And recall that the manifesto speaks for Bob, so he says so as well. But how could Bob have known about the 2008 article when he died in 2006? Clearly there's a contradiction here. (See mechanically generated proof.)

If rather than replacing the manifesto file with metadata about the manifesto, the organization had added a 303 See Other redirection from where the manifesto was to some metadata, the contradiction wouldn't arise.

Perhaps it would be better to find an example that doesn't depend on order of events to get to the contradiction, since we don't really expect complete consistency across time contexts... people change their minds, HTTP responses time out, etc.

perhaps picture in inches, description in centimeters

TODO: Edge case: marginalia, ads

edge case: advertising around the border