Complete.Org: Mailing Lists: Archives: freeciv-ai: April 2002: [freeciv-ai] Re: Approximate win_chance

# [freeciv-ai] Re: Approximate win_chance

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 To: Raahul Kumar Cc: freeciv-ai@xxxxxxxxxxx Subject: [freeciv-ai] Re: Approximate win_chance From: Gregory Berkolaiko Date: Thu, 18 Apr 2002 16:31:28 +0100 (BST)

```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.

```