Re: SAX Filters for Namespace Processing

[John Cowan <cowan@mercury.ccil.org>]

Eric Bohlman scripsit:

> The problem here really isn't "text-based processing."  The "problem"
> is that as much as many geeks would rather it were otherwise, language,
> natural or otherwise, is *always* context-dependent.  The meaning of a
> set of symbols isn't a property of the symbols itself; it comes from an
> external understanding of what they're supposed to mean.  In _Sphere_
> (the book; this part didn't make it into the movie) Michael Crichton
> describes a group of scientists who composed a message intended to
> announce our existence to any extraterrestrials who might be listening.
> The message was based on the values of various physical constants.
> 
> A skeptic among them asked them to do a little thought experiment;
> imagine that they received the same message from space, without knowing
> what it was supposed to be, and try to figure out what it meant.
> None of them could.

In real life, the people that Frank Drake asked to decode his faux
message-from-the-stars did pretty well, and that was nothing but
ones and zeros.  To start with, the number was a product of two
primes, suggesting that it was a raster scan, as indeed it was.
The picture was composed of many subpictures, most of which made
cogent sense: indeed, the most mysterious item was probably the
low-res picture of the aliens (us!) who notionally created it.
See http://www.news.cornell.edu/releases/Nov99/Arecibo.message.ws.html
for details.

> [L]anguage can't carry all of its own meaning.

Fair enough.  Hofstadter's distinction between the inner message
(what we think of as just the message, normally), the frame message
("This message is in Japanese, encoded in Microsoft SJIS"), and
the outer message ("I am a message, decode me if you can!") may be
useful.  XML uses a trick to get the frame message into the
inner message, within reason; similar but more complex things are
done by cryptanalysts.  The outer message, of course, can't be
in either the frame message or the inner message: it is the
outer message that gives trouble in those rocks that may or may
not have runic or ogham inscriptions on them.

-- 
John Cowan                                   cowan@ccil.org
One art/there is/no less/no more/All things/to do/with sparks/galore
	--Douglas Hofstadter