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RE: [Bug-gnubg] Analysis of race rollouts
From: |
David Montgomery |
Subject: |
RE: [Bug-gnubg] Analysis of race rollouts |
Date: |
Thu, 31 Oct 2002 10:11:03 -0800 |
> The power (and limitation) of the OSR is that it is one sided,
> i.e. plays each
> side independently, so that it has no notion if it needs to make
> desperation
> plays or not. Even if it did, I doubt it is possible to find
> those moves cheaply.
>
> -Joseph
It's true that one-sided racing databases that just have the mean
rolls to bear off can't make desperation plays.
But one-sided racing databases with the probability distribution
of rolls to bear off *can and do* make desperation plays, if you
choose plays by convolving the two distributions.
I believe that it will be very rare for a rollout done in this
manner to differ noticably from the exact cpw from a two-sided
database.
If a normal approximation is used, you can still get desperation
plays. Basically the trailer chooses high-variance plays, even
those which might have a slightly higher mean rolls to bear off.
This must be less accurate than using the actual single-sided
distribution, but for positions far from the end of the race, it
probably doesn't give up much.
David