[Bug-gnupedia] The Purity Requirement

[John Goodwin]

I read the announcement () fairly carefully to try to get at
the substance of this proposal.  Here is what I found:

1. About 1/3 of it related to setting scope and organzational
details for the project.

2. Roughly 1/3 dealt with, in effect, the FDL and
what minimum requirements a document would have to
meet to be useable. For ease of wording, I will
call documents that meet these requirements
"FDL-compatible".

3. The real meat amounted to a small set of requirements
on content:

  a. Documents should be FDL or FD-compatible (allow
maintenence, translation, and so forth)

  b. Software examples are free software or open
source--we can take this to mean--GPL or something
that can be used in a GPL system without
compromising it.

  c. Links only point to FDL or FDL-compatible documents

There is also an unstated assumption, I think,
that the web pages will be HTML or at least XML,
and can be served by existing web servers and
viewed by existing browsers.

By far the hardest requirement is (c), the
"purity" requirement--that all links point to FDL
or FD-compatible documents. A document is "pure"
if all its outbound links point to FD-compatible
documents (only).

This amounts to a transitive closure property on
the web pages that comprise the "encyclopedia".
Under the operation "follow the links" you get
only members of the FD-compatible set.

There are two senses in which closure is possible.
Strong closure is the easiest to satisfy: All
links are internal to the subset of FD-compatible
web documents. This makes some connected set of
documents, a subset of all FD-compatible on the
web, closed under link traversal.  You can't
reference things, like cool non-free web pages,
that exist outside the project.

Weak closure envisions a "buffer" zone of FD-
compatible documents which are, however, impure.
These cannot be inside the encyclopedia, because
they are impure, but they can be pointed to,
because they are FD-compatible.  They effect a
transition from the pure zone to the non-free
zone, and allow the Encyclopedia to be somewhat
open.

I think I have stated, formally, what is
distinctive about this proposal.  It is not the
web as we know it today, but a set of documents
inside a particular (defensive) perimeter.  There
are good reasons for wanting this.

=googol=