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RE: [Bug-gnubg] Luck analysis question

From: Albert Silver
Subject: RE: [Bug-gnubg] Luck analysis question
Date: Wed, 11 Jun 2003 11:28:22 -0300

Perhaps one interesting way to examine this would be to run GNU 0.12,
the version that played sgainst Snowie 3.2, and have it analyze the luck
factor and see what the results are. 

The reason I was a bit concerned is this: the luck is NOT independent of
the evaluation of the moves and positions as I see it. It is entirely
dependent in fact. Suppose in a given position, I say the equity is
0.400, move A is the best giving that 0.400 equity, and move B is a
blunder leading to only 0.250. Mind you, this is because I do not
realize that mave B is in fact stronger and leads to 0.450. You
correctly play move B, I play a move that does nothing still thinking it
is only 0.250, and you play a move that improves the position by a mere
0.050. When I analyze this new resulting position, I now see the truth
of it and see that the current equity is 0.500, however having misjudged
it previously will declare you're a lucky guy whose move led to a 0.250

My point being only that the luck factor IS dependent on GNU's
evaluation as far as I can see. As to the variance reduction in
rollouts, it is different. Variance reduction doesn't guarantee the
rollouts will be correct, it just reduces the number of trials needed to
reach the same result of a larger number of trials without variance
reduction. Thus I can get the right or wrong result with only 1000
trials instead of 10,000.


> -----Original Message-----
> From: address@hidden [mailto:bug-gnubg-
> address@hidden On Behalf Of Joern Thyssen
> Sent: Wednesday, June 11, 2003 10:58 AM
> To: GNU Backgammon Bugs
> Subject: Re: [Bug-gnubg] Luck analysis question
> On Wed, Jun 11, 2003 at 09:55:18AM -0400, address@hidden wrote
> > In a message dated 11/06/2003 14:50:55 GMT Daylight Time,
> > writes:
> >
> >
> > > If I analyse the matches with gnubg, it will say that snowie is
> > > up equity /relative/ to gnubg, and vice versa. Since we do not
have a
> > > perfect bot for analysing cube decisions and chequerplays, the
> > > thing we can do is to play a huge number of matches between the
two. I
> > > calculated the luck adjusted results to reduce the variance
similar to
> > > what we do in rollouts.
> > >
> > > Jørn
> > >
> > >
> >
> > Or we could roll out all the disagreements using both bots and that
> should
> > give us some good ideas.
> > In my series between GNU and S3.2, Snowie won easily after 100 games
> must
> > have been quite lucky because rollouts by SW3.2 show GNU to be
> yes, but calculating luck adjusted results are much faster than
> performing many rollouts.
> Also, rollouts may still disagree.
> Jørn
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