Re: Formalization of the Artificial Life Systems

[Barry McMullin]

Vladimir Jojic writes:
 > 
 > Formalization of the Artificial Life Systems
 > (very informal)
 > 
[...]

 > I am trying to develop a simple formal definition of the artificial life
 > systems, and some techniques for solving some standard problems by using
 > the formal approach. 

[...]

 > Send me an e-mail if:  
 > 
 > - you think this won't work and you know why it won't work ...
 > 
 > - you know that this, or anything similar has been done (and have some
 > proof of that, reference for example) or you are working on it
 > 
 > - you have access to early autonomous agents works (I don't! :( and you
 > could tell me how they defined it
 > 
 > btw. I am not saying that descriptive definition is not good, actually I
 > will be using it as the basis for the whole thing (implicitly)
 > 
 > 
 > Every advice, suggestion or an answer to a question mentioned above will
 > be appreciated,
 
Hi Vladimir -

I think tHese are very interesting questions, and I
would *love* to here more from you as you progress with
them.

I'm interesting in "autonomous agents" in the sense
that living things are autonomous.  Work related to
formalisation of such agents that I am at least
somewhat familiar with includes:

1: Varela & Maturana's notion of autopoiesis.  I think
this is an important and powerful idea - but find that
it is still too informal (vague) to do any real work
with.  I believe Varela made some serious effort at
formalisation, drawing on Spenncer-Brown's "calculus of
indications" - this is dealt with in Varela's book
"Principles of Biological Autonomy" (c. 1980, not sure
of the publisher offhand).  But my understanding is
that Varela never really succeeded in this enterprise
and eventually left this attempt at formalisation aside.

2: Robert Rosen has addressed this over a long number
of years, starting with his "M-R" (metabolism-repair)
systems, c. 1960, up to his recent work applying
category theory (see "Life Itself", c. 1993 I think).
I'm tantalised by Rosen's work but am not
mathematically competent enough to really understand or
assess it.

3: George Kampis has also invested a lot of effort in
this area (http://hps.elte.hu/kampis.html).  His URL is
not responding for me just now, so I can't check the
details, but he had a very nice book a few years ago
(c. 1990 I think) called something like "Self Modifying
Systems".

4: Here in SFI, Stuart Kauffman has been recently
tackling this kind of problem.  He has a lengthy
technical report online, called "Investigations", where
he reviews his current thinking:

  http://www.santafe.edu/sfi/People/kauffman/Investigations.html

5: Walter Fontana and Leo Buss have also expended a lot
of effort on this.  I'd especially recommend Buss'
book, "The Evolution of Individuality" for a very
biological perspective. They also have a technical
report available from SFI:

  http://www.santafe.edu/sfi/publications/Working-Papers/96-05-035.ps
  The Barrier of Objects: From Dynamical Systems to Bounded Organizations
  Walter Fontana and Leo W. Buss
  To appear in Boundaries and Barriers: On the Limits to 
  Scientific Knowledge edited
  by J. Casti and A. Karlqvist. Reading, MA: Addison-Wesley, 1996. 


============================

I hope that gives you some additional ideas.  The
problem I'm most concerned with at the moment is
whether or not there is a fundamental clash between the
formalisation of autonomous agents and dynamical
systems theory (in the broadest sense). 

In *my* sense, "autonomous" agents are, inter alia,
"materially open" - they are composite systems whose
components, and even distribution of components, change
over time, even though the "system itself" persists.

This is very different from composite systems
consisting of a *fixed* set of components.  For the
latter case, the formal model of the "system" is a more
or less direct combination of the formal models of the
components (and their "interconnections").  But such a
"reductionist" analysis does not seem to be possible
for "materially open" systems.  In fact, it seems that
such systems would not even have a fixed state space in
which their dynamics might be defined.  So, it seems to
me that such systems *cannot* be satisfactorily
formalised with any of the machinery of dynamical
systems (whether discrete, continuous, finite,
infinite, chaotic or not; I even include "computation
theory" here in the sense that "computers" are simply
particular classes of dynamical systems...).  

I don't know how, or if, this relates to Vladimir's
attempts at formalisation, but I would appreciate
comments from him or anyone else who can shed any light
on these issues.

Regards,

Barry.


-- 

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| Barry McMullin, ALife Group,               |    address@hidden |
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