[FRIAM] Formal Definition of Agent Based Model

[Marcus G. Daniels]

Phil Henshaw wrote:
> That would somewhat model the occurrence of 'emergent cells'
> of new systems of relationships that are 'feeding on' rather than being
> 'determined by' their environments.
>   
To my way of thinking, a `type correct' computer program behaves 
somewhat like a fit individual in a biological system.  But it's not 
very realistic since type consistency is global property of a program.   
If you fiddle with a subcomponent of a Java program, for example, the 
compiler will tell you if you did something wrong and not let you run 
the program.   In a biological system the corresponding subcomponent 
might not get exercised enough to change the fitness of the individual 
much.  Fitness is both a function of the environment and the 
individual.   For example, given a large population of individuals and 
few of them are in the situation in the environment where changes to a 
part of there genome would kill them, it doesn't matter if that change 
is, in principle, inferior.  By `in principle' I mean there are easy to 
imagine environments where it would be inferior.  In a computer program 
I mean that a code path has operands and operators that are incompatible.

For me, it's initially easier to write some kinds of computer programs 
that are not type safe (e.g. to use scripting languages) because I don't 
have to think about how all of the pieces fit together.  It's like not 
pounding all of the nails all of the way down.    Attention can be 
focused in writing a new part of a program and once the logic is worked 
out, the details of the interface can be decided to safely connect it to 
the rest.   The larger program or set of programs can even be running 
while this logic is worked out.   I think this kind of flexibility is 
pretty important for evolution and missing in a lot of ABM and ABM tools.