Re: Complex computer programs

From: Richard Loosemore (
Date: Mon Sep 12 2005 - 14:54:35 MDT

Phil Goetz wrote:
> --- Richard Loosemore <> wrote:
>>Phil Goetz wrote:
>>>--- Phil Goetz <> wrote:
>>>>Not that I can think of any good examples of heterogenous
>>>>complex systems.
>>>Rule-based systems. Computer programs in general.
>>Depends, and No.
>>Computer programs are almost always not Complex (capital C).
> I disagree. I've written many massively-multithreaded agent-based
> systems. For instance, the airspace simulator I wrote ran about
> 20,000 agents, each running on its own virtual thread, and each
> capable of interfering with any other agent.
> Also, much complex systems work has been done using computer
> simulations! If those simulations aren't complex, then...

I should have stuck to your original wording! ;-)

What I should have said was:

"Computer programs *in general* are almost always not Complex."

Did your agents evolve their behavior substantially in the course of
interacting with other agents? This would be the crucial factor to look
for. Not just a small change of parameters, but the kind of change that
makes them almost become different programs? Now, if they did, we might
expect some complex behavior. What I was trying to say was that most
programmers do not put that level of evolution (adaptiveness) in their
code. And because they don't, it is hard to get any of the interesting
facets of complexity to show up.

I mean, if I looked at the Microsoft Word codebase, I doubt I would find
most of the functions written in such a way that next week they will
have modified themselves so they were now carrying out different
algorithms. A few examples of adaptation, maybe, but I can be pretty
sure that the Redmond folks didn't code it so everything was looking at
everything else and adjusting its behavior all the time!

[Or, then again.... ;-)]

Richard Loosemore

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