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[freeciv-ai] Re: Approximate win_chance

[freeciv-ai] Re: Approximate win_chance

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To: rf13@xxxxxxxxxxxxxxxxxxxxxx
Cc: Raahul Kumar <raahul_da_man@xxxxxxxxx>, "Ross W. Wetmore" <rwetmore@xxxxxxxxxxxx>, Gregory Berkolaiko <Gregory.Berkolaiko@xxxxxxxxxxxx>, freeciv-ai@xxxxxxxxxxx
Subject: [freeciv-ai] Re: Approximate win_chance
From: "Ross W. Wetmore" <rwetmore@xxxxxxxxxxxx>
Date: Wed, 24 Apr 2002 20:17:47 -0400

At 02:02 PM 02/04/24 +0200, Raimar Falke wrote:
>On Wed, Apr 24, 2002 at 04:08:41AM -0700, Raahul Kumar wrote:
>> <snip>
>> > Bottom line for me: the proposed approximation is much to fragile.
>> I'm not with you on the logic train. Let's slam the brakes. Greg's
>> approximation is far better than the current one, which just squares the
>> results.
>AFAIK the current win_chance isn't an approximation but returns the
>exact value. Or do I'm mistaken about that?

If I am not mistaken, you cannot compute the exact value since that is
determined randomly. And if you are only estimating the chance, then
"exactness" is not a particularly hard criteria - certainly not the
determining one.

>> It has a much smaller absolute error and and the error occurs fewer
times than
>> the current implementation. That's good enough for inclusion.

This is a more sensible way to approach this kind of thing.

The only thing to add is maybe some "risk" assessment that it won't be bad
in a particularly sensitive area.

>> > 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 
speed differential should seem to be the overwhelming consideration.
Even the explicit win_chance() computation is probably worth throwing 
out when it is that expensive in comparison for no significant increase
in benefit.

>       Raimar
> email: rf13@xxxxxxxxxxxxxxxxx
>  "brand memory are for windows users that think their stability
>   problems come from the memory"
>    -- bomek in #freeciv


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