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RE: [Bug-gnubg] Beaver bug
From: |
Albert Silver |
Subject: |
RE: [Bug-gnubg] Beaver bug |
Date: |
Thu, 31 Jul 2003 00:46:49 -0300 |
Did you look at the stats it is producing? I saw it alternate from
favorite to lost in each ply. At ply 0 it says it has 7.9% chances to
win but at 1-ply it says it has 67.8%. Now *that's* odd.
Albert
> -----Original Message-----
> From: address@hidden [mailto:bug-gnubg-
> address@hidden On Behalf Of Christopher D. Yep
> Sent: Thursday, July 31, 2003 12:21 AM
> To: address@hidden
> Subject: [Bug-gnubg] Beaver bug
>
> Sometimes gnubg doesn't report beavers correctly. For example,
consider
> the following extreme position:
>
> GNU Backgammon Position ID: Pp8PAAAAAPh8Pg
> Match ID : cAkAAAAAAAAA
> +24-23-22-21-20-19------18-17-16-15-14-13-+ O: gnubg
> | X O X O X O | | | 0 points
> | X O X O X O | | |
> | X O X O X O | | |
> | X O X O X O | | |
> | X O X O X O | | |
> | |BAR| |v (Cube: 1)
> | | | |
> | | | |
> | | | |
> | | | | On roll
> | | | | 0 points
> +-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: Chris
> Pip counts: O 60, X 330
>
> X is playing an extreme 15-checker backgame. X owns the cube and is
on
> roll.
>
> 0-ply, 1-ply, 2-ply, and 4-ply analysis (no reduced evaluations) all
state
> that X is a cubeless underdog. Therefore, 0-ply, 1-ply, 2-ply, and
4-ply
> evaluations should definitely be no-redouble/beaver. However gnubg
says
> it's no-redouble/take at 0-ply, 2-ply, and 4-ply. At 1-ply it
correctly
> says that it's a no-redouble/beaver.
>
> I'm using gnubg for Windows version 0.14-devel 1.1227 030727 (build
Jul 27
> 2003).
>
> Here is gnubg's display for 0-ply through 4-ply (for both the hint and
> evaluations windows):
>
> 0-ply:
>
> Cube analysis
> 0-ply cubeless equity -2.120
> 7.9% 0.0% 0.0% - 92.1% 87.0% 40.8%
> Cubeful equities:
> 1. No double -2.093
> 2. Double, pass +1.000 ( +3.093)
> 3. Double, take -4.297 ( -2.204)
> Proper cube action: No redouble, take (41.6%)
>
> 1-ply:
>
> Cube analysis
> 1-ply cubeless equity -0.012
> 67.8% 0.2% 0.0% - 32.2% 26.6% 10.4%
> Cubeful equities:
> 1. No double +0.218
> 2. Double, pass +1.000 ( +0.782)
> 3. Double, take -0.243 ( -0.462)
> Proper cube action: No redouble, beaver (37.1%)
>
> 2-ply:
>
> Cube analysis
> 2-ply cubeless equity -2.091
> 7.5% 0.0% 0.0% - 92.5% 86.5% 37.5%
> Cubeful equities:
> 1. No double -2.066
> 2. Double, pass +1.000 ( +3.066)
> 3. Double, take -4.237 ( -2.172)
> Proper cube action: No redouble, take (41.5%)
>
> 3-ply [note: the bug doesn't apply here; the interpretation of
> no-redouble/take is correct since .139 > 0]:
>
> Cube analysis
> 3-ply cubeless equity +0.159
> 73.7% 0.1% 0.0% - 26.3% 22.0% 9.6%
> Cubeful equities:
> 1. No double +0.414
> 2. Double, pass +1.000 ( +0.586)
> 3. Double, take +0.139 ( -0.275)
> Proper cube action: No redouble, take (32.0%)
>
> 4-ply:
>
> Cube analysis
> 4-ply cubeless equity -2.027
> 6.9% 0.0% 0.0% - 93.1% 85.1% 31.3%
> Cubeful equities:
> 1. No double -2.004
> 2. Double, pass +1.000 ( +3.004)
> 3. Double, take -4.107 ( -2.104)
> Proper cube action: No redouble, take (41.2%)
>
> Chris
>
>
>
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