From: robd@cherry09 (Robert Derrick)
Subject: Re: Data Structures of Unreality
X-Newsreader: Tin 1.1 PL5
Date: 26 Aug 92 19:39:19 CDT

Alan Smith (arsmith@nyx.cs.du.edu) wrote:
: robd@cherry09 (Robert Derrick) writes:
: >Drew Lawson (lawson@acuson.com) wrote:
: >: 
: >: Interesting.  A "physical chunk of memory" is not a data structure.
: >: Likewise, an object is not its representation.  When you get to the
: >: machine execution, data structures do not exist.  But they are
: >: convenient notions for organizing many details.
: >
: >Ah!  And would you also concur that a strand of DNA is not a human
: >being?  The object "human" is not its representation "DNA".  Is this
: >correct?  When you get to the implementation and operation of a
: >human, does the coding within the data structures in the cells not
: >exist?  Are the DNA codes just convenient notions for organizing
: >many details?
: >
: >I really want to hear your answer.
: >

: I don't think that's what he meant.  I think that he meant that the symbol
: for something and that thing are usually two different things.  (God help
: you if you believe otherwise)  Which, so far as it goes, is true, he just
: picked a bad example.  But so did you.

Well, to tell you the truth, I don't really know what he meant.  But I
know what he said.  And a data structure, in use, is not just a symbol
for something, like 'Big Al' is a symbol for you.  It is an encoding
of information, and DNA is also an encoding of lots of information.
One could easily make the argument that the DNA itself is a program
built of executable code and also data structures, which executes 
within the hardware of a cell.  This is an oversimplification, but
not unreasonable.

He said, "when you get to the machine execution, data structures do
not exist."  This is not true, for not only are there software
data structures, that you all seem to believe have some kind of
ethereal Zen-like existence, but there are also hardware data
structures, manipulated by hardware instructions, and they are
very real!  They are not just "convenient notions" in a chunk of
memory.  They are essential to the operation of the machine.
Now just because I can run a general purpose program on a given
architecture that the hardware designers did not envision, that
does not make that program and its data structures any less real.

The fact of the matter is that a cell is the world's best general
purpose computer and a marvel of subminiaturation.  It can run
a vast array of DNA programs, many of which will produce a very
useful result.

: Computers deal exclusively in symboligy (Unless you want to say they deal
: exclusively in electric current, but that's not what I meant) computers do
: *not* deal with physical objects.  So a data structure that is "imlemented
: and operated" does not necisarily effect the physical structure that it
: represents.  The same thing works the other way, the physical object does
: not necissarily effect the data structure.

Your first example is not a necessary constraint of the data structure.
There is no natural law that forbids the data structure from modifying
the physical components of the machine that it is in.  It just hasn't
been done yet (that I know off).  But it is definitely not beyond
possibility, and in the area of nanotechnology, will likely become
de rigeur.  And now that I think of it, at present there are systems
that produce physical objects based on information stored in
data structures -- data structures which can be said to represent 
those physical objects.  This is known as modern manufacturing.

Your second example is clearly false, because the physical object I
am using right now is at this moment effecting the data structure that
I am in the process of manipulating.

In the case of the world's best computer, the brain, I guess you could
say that the data structures within it are only symbols, and that they
do not effect objects in the real world.  But then I would say that I felt
that solipsism was a bankrupt philosphy, so why bother.

: Your analogy, a DNA strand to a human being, is not the same.  DNA is an
: intigral part of a human, without it they wouldn't exist.  Besides, to my

And data structures are an integral part of a running computer.  A
piece of hardware without a program would be the same as a blank
strand of DNA within a cell (envision that how you will).  Or as a fully
functional and running human being without a brain.  Without the data structures
and the programs that manipulate them, they are equivalently useless,
although existent.  The hardware and the software are both essential
to the useful operation of the computer, the DNA, and the human being.

: knowledge, DNA has never been used to identify someone in conversation. 
: However, I have often seen people identified by symbols that wouldn't
: alter them in the least should those symbols be changed.

Alter a data structure in a running program (with computer, DNA or brain
as your hardware, and see if that doesn't change the essential
character of the end result of the process in question.

: Anyway, my point is is that a non incorporated symbol is different from an
: incorporated structure, even though the structure does contain symbols for
: the makeup of other structures.
: 
: Big Al.  What the *hell* did I just say???

Damned if I know.  But you seem to think, as many designers of
computer architecture in the past have thought, that software
is somehow not an essential part of the computer.  That you can
build your computer, deliver it, and somehow, your job is complete.
The marketing of computers over the years have proved that
people who pay money for computers do not hold this opinion.
As a matter of fact, most consumer analysts will tell you that
it is the Software that is the most important component of a
computer system, and if you are shopping for one, you should
decide on the software first, and then find the hardware that
runs it.  Evolutionarily speaking (bet you all thought we'd
never get around to that), it is the software that defines
the hardware, and will determine the survivability of the
machine.  If you doubt that, then I suggest you ask
Seymour Cray how many of the world's fastest computers you
can sell without an operating system.  And also find out why
Cray computers now run UNIX as its collection of 'non incorporated
symbols'.

rob derrick
Newsgroups: sci.skeptic