Newsgroups: comp.ai.games
Path: cantaloupe.srv.cs.cmu.edu!rochester!rit!sunsrvr6!tro
From: tro@cci.com (Tim Oertel)
Subject: Re: Help with computer ai for galactic war game
Message-ID: <D974K3.9rr@sunsrvr6.cci.com>
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References: <3paa7b$c13@nbc.ksu.ksu.edu> <3pm6av$1eu8@news.gate.net> <SROBERTS.95May21054409@idiom.com> <3ps687$fbs@gaia.ucs.orst.edu>
Date: Fri, 26 May 1995 17:28:50 GMT
Lines: 61


Note, I'm not including everything that has been floating around here because
I think much of it has been reprinted PLENTY...

I caught this thread in the middle and missed some of the original posts, but
from what I've seen, here are some observations:

 o You might have problems using GAs if the population size is small (esp. in
   the begining, when your fleet has 6 DESIGNS, but it actually has only 2 
   ships actually produced).  I don't know a good solution to this, other than
   using a baseline of ships, like has been suggested previously.

 o I suspect that you don't need to deliberately balance the fleet, as long as
   the fitness equation is set up correctly.  As long as the GA side is winning
   who CARES what sort of fleet it has.  (I've found that I can often CRUSH
   the computer players using a very lopsided approach in Civ. and MOO.  My
   biggest strategy is to take a hold of a few planets in MOO, build them
   defensively strong and a few ships to keep the enemy at bay, and throw all
   available resources at technology.  In not too long my tech far outstrips
   the enemy, and I can expand slowly.  Similar thing can be done in Civ.  I've
   played games where I've had jets and tanks, while the enemy was still moving
   around in chariots... but I digress.)

 o There are a number of ways to adjust the difficulty level of the computer
   player, including the already mentioned "time to simulate".  Another option
   is to adjust some subset of the fitness variables.  For example:

   Kill value  (value of ships destroyed, in resources or man years...)
               (perhaps this is on a per "race" basis?)
   Number of battles  (strictly number of battles)
   Number of battles survived
	Flee value  (value of ships that fled a battle)
   Number of planets conquered  (or planets colonized..)

   Each field above has a coefficent associated with it which weights its
   importance in the overall fitness value.  Increasing the value of the
   "Flee value" and "Number of battles survived" increases the defensiveness
   of the GA, whereas increasing the value of the "Kill value" increases the
   offensiveness of the GA.  You could certainly add a whole collection of
   other variables that are less directly related to given battles... like:

   How many planets have recently been conquered
   How much has our technology advanced (this might DECREASE the fitness)
	How much has the enemy's tech advanced (also dec. the fitness)
   How much has trade increased recently
   Cost to produce (this should be low)
   Time to produce (this should also be low)

 o If your mutation rate is too high, you may have problems with your
   population not stablizing (during the simulated runs), i.e. you may have
   a number of different designs that all have about the same fitness value,
   but you really only want one or two...


---> Tim

-- 
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"Why should I be content to simply   //  tro@sunsrvr6.cci.com
 live in this world, when I, as a   // 
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