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[freeciv-ai] Re: Approximate win_chance

[freeciv-ai] Re: Approximate win_chance

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To: Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx>, rf13@xxxxxxxxxxxxxxxxxxxxxx
Cc: "Ross W. Wetmore" <rwetmore@xxxxxxxxxxxx>, Raahul Kumar <raahul_da_man@xxxxxxxxx>, freeciv-ai@xxxxxxxxxxx
Subject: [freeciv-ai] Re: Approximate win_chance
From: Raahul Kumar <raahul_da_man@xxxxxxxxx>
Date: Thu, 25 Apr 2002 17:13:24 -0700 (PDT)

> > > [...]
> > > >> > Bottom line 2: we have to carefully select the set of values we test
> > > >> > the approximation against. Best would be the whole possible set of
> > > >> > values. Or a real (not by simulation) mathematical calculation of
> the errors we have to expect.
> > > >> 
> > > >> Not asking for much are you?
> > > >
> > > >As I said this would be the ideal solution. If the current win_chance
> > > >returns the correct value we have to have an estimation of the error
> > > >which a new win_chance will produce.
> > > 
> > > I think the estimations have been done. They seem to indicate that the
> > > 5th power solution is better than the current 2nd power one and almost
> > > indistinguishable from the more explicit estimation of chances.
> > 
> > > Since none of this really affects anything critical in the game, the 
> > 
> > And this is a question which is still unanswered for me: How do you
> > (the ai developers) that a particular code construct needs the "exact"
> > value (as returned by win_chance) and when does it can cope with an
> > approximation (which has an average/maximal error of something)? I
> > suspect that you don't do this decision based on hard facts.
> Hard facts are hard to come by.  Things are not black and white, 
> especially in a game with such complicated rules.

As far as combat as concerned, we are dissatified with the current
approximation. It's very bad. Those non significant errors Greg mentions
mount up over the course of the game. We do make the decision based on hard
facts. Greg did some simulations that showed the current AI was making the
wrong decisions in a few cases(Stealth bomber vs partisan) due to the
inaccuracy of the current implementation. With Greg's improved
approx_win_chance, the AI will do better. Better understanding of the combat
odds is always good. 

Using your suggested error tolerance method would be great if we had a method
to calculate in advance without calling win_chance what the error % is.
> The decision made by the AI is not a critical one (a missed opportunity 
> to inflict some damage) and if a better approximation can reduce the 
> number of such non-critical errors without pushing the time up, it is 
> good.  


Tourist, Rincewind has decided, meant idiot. (Terry Pratchett)

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