[freeciv-ai] Re: Approximate win_chance

[Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx>]

On Thu, 18 Apr 2002, Raahul Kumar wrote:

> --- Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx> wrote:
> > I ran some simulations with my approximate win_chance formula.
> > 
> > It doesn't perform as well as I initially thought, but it's definitely 
> > better than the current system we have in most AI routines.
> > Current system:
> > 
> > A_rating = A_strength * A_HP * A_FP;
> > D_rating = D_strength * D_HP * D_FP;
> > 
> > chance = A_rating^2 / ( A_rating^2 + D_rating^2 )
> > 
> > My formula:
> > 
> > chance = A_rating^5 / ( A_rating^5 + D_rating^5 )
> 
> I believe diminishing returns kick in sharply. Would using the formula 
> 
> chance = A_rating^6 / ( A_rating^6 + D_rating^6 )
> 
> fix the problem of absolute error sometimes being 15%. You should have
> mentioned how often those values crop up. 

Power 5 works best (better than 4 or 6).  Not very often.  You can 
experiment with the code I attached.

> > This performs way better but for some weird cases it still gives an 
> > absolute error of about 15%.
> > 
> 
> Is there any way we can avoid calling approx win_chance when that happens?

The problem is that I don't know beforehand when such thing would happen.  
But I am still thinking about it...

G.