[Freeciv-Dev] Re: Bombers/Fighters no longer obsolete (PR#1628)

[Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx>]

On Fri, 28 Jun 2002, Raimar Falke wrote:

> On Fri, Jun 28, 2002 at 04:52:26PM +0100, Gregory Berkolaiko wrote:
> > On Wed, 26 Jun 2002, Ross W. Wetmore wrote:
> > 
> > > Of course this implies that your attack power formula actually 
> > > means something rather than being one of many heuristic formulae
> > > none of which describes reality in any accurate way :-).
> > 
> > I would like to point out that the formula used by Raahul does describe 
> > reality in a pretty accurate way.  And I can give you a solid 
> > justification why it is so.  As a matter of fact, I'll give you few hints 
> > and can fill in the rest.  Since excercise is good for you ;)
> > 
> > We have an attacker A with stats (S_A, HP_A, FP_A) and 
> > a defender D (S_D, HP_D, FP_D).  We want to decide which one is stronger.  
> > And of course by "stronger" we mean "which one has larger probability to 
> > win a fight when A attacks D".
> > 
> > Lets assume FP_A = FP_D = 1.  Otherwise we can substitute 
> >     HP_A <- HP_A / FP_D
> > etc.
> > 
> > 1. You can compute the win_chance and try to analyse it.  But that is too 
> > tough :(
> > 
> > 2. Alternatively you can say, lets count how many successful hits will A
> > score, _on_average_, before it dies.  If this _average_ number of hits
> > will be greater that HP_D, then the defender will die, on _average_,
> > before the attacker does.  Which implies that the attacker will succeed in
> > more fights than the defender.
> > 
> > 3. So we are running a random process giving us 0s and 1s.  0 means A won 
> > the round, 1 means D won the round.  The question we have to answer is how 
> > many (on avergae) zeros will come up before we see HP_A ones. 
> > 
> > 4. Probability of having 0 is 
> >     S_A / (S_A + S_D),
> > probability of getting 1 is
> >     S_D / (S_A + S_D).
> > The rounds are independent.
> > 
> > 5. Now, instead of inventing 20 + 20 formulae, you, Ross, should get 
> > yourself a "probability for kids and gamblers" book and calculate the 
> > answer. :)
> 
> This is all clear but misses the point. The hypothesis is the military
> power/value of a unit is "S_A * HP_A * FP_A". And I don't see a line
> in code in combat.c which multiplies the three except
> get_defense_rating which as the name suggests is a rating.

You think it misses the point because you didn't do the calculation.  Or 
maybe even didn't read the email ;)

> Note that all these leave out other factors like increased move_rate.

I am afraid the increased move_rate cannot enter the win_chance 
calculations.

G.