🚀 go-pugleaf

In article <4880f240.20b6d@apollo.HP.COM> nelson_p@apollo.HP.COM (Peter Nelson) writes:

>  I am curious to learn more about such self-organizing-systems.
>  The natural world is full of examples of how microscopic 
>  features or behavior produce macroscopic structures.   The 
>  shape of my hand or the shape of a leaf is similarly the
>  result of lots of individual cells responding individually 
>  to local effects (which is not to say that the "local" 
>  environment" to the cell may not be affected by chemicals 
>  emitted by cells a great distance away and dissusing through
>  the tissue).
>  
>  Are there any general principals that may be applied to 
>  problems like this in simulations?   If I wanted to create 
>  a CA program that would produce a particular shape, say a 
>  star or a triangle, is there any systematic way to go 
>  about it?                         
>
>                                              ---Peter

Another interesting self-organizing system created solely by local
action is a free marketplace.

Another interesting self-organizing system that can be interpreted as
evolutionary is the erosion of land: the formation of valleys between
ridges with the valley streams merging to form tree structures rooted
at the ocean.  Let me make the analogy explicit: 

Evolution requires:

1. heritable variation, ie, as the state of a system (usually the
gene pool of a species) progresses through time, new states resemble
previous ones but not entirely.

2. evaluation and differential reproduction (natural selection).

Take the positions and orientations of rocks to be the state of a
geological system.  Look at how that state changes over time.
'Stable' substates tend to exist for longer amounts of time.
Weathering processes perform natural selection on the positions of
rocks and dirt.  An example of a stable substate is a flat rock lying
on its broad side; an unstable state would be that rock on edge.
Random perturbations such as rain drive the search for stable
configurations much as mutation (and crossover) drives the search for
novel genotypes.

Note that individuals within the population (rocks on the same
hillside) interact, and influence each other's evolution.  For
instance, two rocks may together block a stream and thus slow their
tumbling down the hill.

Local forces involving the local slope of the land, gravity, and water
flow result in mountains with globally self-similar ridges and streams
(both ridges and rivers form tree structures, the latter draining the
former).
--
David A. Honig		

"Live Free Or Don't"