announce.30

地球模拟器

                             TIERRA UPDATE:
  (Mailing lists, Source code, abstract, publications, lectures, new results)

This message contains:

1) Announcement of Tierra mailing lists
2) Major Tierra upgrade, and Beagle now available
3) Availability of Tierra source code
4) Abstract describing Tierra
5) List of related publications and upcoming lectures
6) Some interesting new and unpublished results

     Due to your interest in the Tierra software, you have been placed on
a mailing list.  To have yourself removed, send a message to:
[e-mail], requesting that you be removed.

     There is a mailing list for Tierra users. (actually 3, but you only want
to be on one of them).  The first list is for people who only want to get the
official announcements, updates and bug-fixes. The other two will carry the 
official postings, and are intended for discussion of tierra by users.  One 
of these is distributed in digest form, when there is enough material; the
other is set up as a mail reflector--postings will go out to the whole list
immediately.  The lists are:

tierra-announce    official updates, patches and announcements only
tierra             discussion, updates, etc. (immediate delivery)
tierra-digest      same as above (once per day digest form)

The addresses are: 

[e-mail]   the list administrator. to be added,
                                    removed, or complain about problems with
                                    any of these lists.
[e-mail]   or
[e-mail]    to post to the list.

[e-mail]       for bug-reports or questions about the
                                    code or installation.

2) Major Tierra upgrade, and Beagle now available

     A major rework of the genebank manager has been largely completed and
is now available in the ftp site.  The work was done mostly by Tom Uffner,
with a little help from Tom Ray (many thanks to Tom U!).  If you picked up
the original release, it would be well worth your while to pick up the new
version.  Also, a DOS executable of the Beagle program, and documentation,
are available in the /tierra/beagle directory of the ftp site.

3) Availability of Tierra source code

     The source code is available now, although it is under rapid development
and major improvements always underway.  If you use the software, be sure
to pick up new versions soon from the ftp site.  The source in the ftp site
will be replace on a roughly weekly or monthly basis.

     The complete source code for the Tierra simulator is
available by anonymous ftp at:

tierra.slhs.udel.edu [128.175.41.34] and
  life.slhs.udel.edu [128.175.41.33]

in the directories /tierra and /tierra/beagle.

to get it, ftp to tierra or life, log in as user "anonymous" and give your
real name (eg. [e-mail]) as a password.

then give the command `cd tierra', to get a list of files type `dir'.

you will see the following files:

README.T1		A detailed description of tierra and how to use it.
README.T2		    in two parts
Part01			the source code in shar format
 ...			    in seven parts
Part07
announce    		this announcement
tierra1.tex		Parts 1 & 2 of a manuscript describing Tierra,
tierra2.tex		    in LaTeX format.

The shar files contain the README files, so if you want the source code,
you don't need to copy README separately.  To unpack the shar files, use
`unshar', or `sh'.

     The version released includes significant contributions from
Tom Uffner, Dan Pirone and Marc Cygnus.  The software remains copyrighted
("all rights reserved"), and is not being placed in the public domain.
However, it will be made available free of charge and may be freely
distributed.  The intent is that it not be used for profit making activities
unless some royalty arrangement is entered into with the authors.

     A DOS version of the Tierra software with a decent frontend will be ready
for sale ($70) by November.  Note however, that the version of the source
code in the ftp site will compile with Turbo C, and run under DOS.

4) Abstract describing Tierra

**** BEGIN ABSTRACT ****

Synthetic organisms have been created based on a computer metaphor of
organic life in which CPU time is the ``energy'' resource and memory is
the ``material'' resource.  Memory is organized into informational
patterns that exploit CPU time for self-replication.  Mutation generates
new forms, and evolution proceeds by natural selection as different
genotypes compete for CPU time and memory space.

Observation of nature shows that evolution by natural selection is
capable of both optimization and creativity.  Artificial models of evolution
have demonstrated the optimizing ability of evolution, as exemplified by
the field of genetic algorithms.  The creative aspects of evolution have been
more elusive to model.  The difficulty derives in part from a tendency of
models to specify the meaning of the ``genome'' of the evolving entities,
precluding new meanings from emerging.  I will present a natural model of
evolution demonstrating both optimization and creativity, in which the
genome consists of sequences of executable machine code.

From a single rudimentary ancestral ``creature'',
very quickly there evolve parasites, which are not able to replicate in
isolation because they lack a large portion of the genome.  However, these
parasites search for the missing information, and if they locate it in a
nearby creature, parasitize the information from the neighboring genome,
thereby effecting their own replication.

In some runs, hosts evolve immunity to attack by parasites.
When immune hosts appear, they often increase in frequency, devastating the
parasite populations.  In some runs where the community comes to be
dominated by immune hosts, parasites evolve that are resistant to immunity.

Hosts sometimes evolve a response to parasites that goes beyond immunity,
to actual (facultative) hyper-parasitism.  The hyper-parasite deceives the
parasite causing the parasite to devote its energetic resources to replication
of the hyper-parastie genome.  This drives the parasites to extinction.

Evolving in the absence of parasites, hyper-parasites completely dominate
the community, resulting in a relatively uniform community characterize by
a high degree of relationship between individuals.  Under these circumstances,
sociality evolves, in the form of creatures which can only replicate in
aggregations.

The cooperative behavior of the social hyper-parasites makes them vulnerable
to a new class of parasites.  These cheaters, hyper-hyper-parasites, insert
themselves between cooperating social individuals, deceiving the social
creatures, causing them to replicate the genomes of the cheaters.

The only genetic change imposed on the simulator is
random bit flips in the machine code of the creatures.  However, it turns
out that parasites are very sloppy replicators.  They cause significant
recombination and rearrangement of the genomes.  This spontaneous sexuality
is a powerful force for evolutionary change in the system.

One of the most interesting aspects of this instance of life is
that the bulk of the evolution is based on adaptation to the biotic
environment rather than the physical environment.  It is co-evolution
that drives the system.

**** END ABSTRACT ****

5) List of related publications and upcoming lectures

    The recent publicity about my work (Technology Review, April 1991;