[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Bug-gnubg] Re: Beaver bug
From: |
Christopher D. Yep |
Subject: |
[Bug-gnubg] Re: Beaver bug |
Date: |
Wed, 30 Jul 2003 23:49:40 -0400 |
To answer my own bug report, I forgot that beavers may be dropped. gnubg
is actually giving correct interpretations of its 0-ply, 2-ply, and 4-ply
evaluations. At 0-ply, 2-ply, and 4-ply, O is actually *too good* to
beaver since the reported normalized equities for redouble/take (4.297,
4.237, and 4.107 respectively) are > 2.000. If O mistakenly beavers, X
should pass the beaver, giving up only 2 times the original cube value.
Also note that I gave a centered cube in the original diagram, but actually
I tested it with X owning the cube; I then forgot to change the diagram
before posting.
I tested gnubg with a variety of extreme positions and found that the
interpretations of its evaluations always made sense. Impressive!!
BTW, I'm not bothered that gnubg's evaluations are way off for this
position since it's an "extreme" position.
Here's the original position (corrected):
GNU Backgammon Position ID: Pp8PAAAAAPh8Pg
Match ID : UQkAAAAAAAAA
+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
| | | |
| | | |
| | | |
| | | | On roll
| | | | 0 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: Chris (Cube: 2)
Pip counts: O 60, X 330
Here are the relevant equities mentioned above:
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%)
The above is correct; if X redoubles, O should not beaver since 4.297 >
2.000. If O mistakenly beavers, X should drop the beaver, losing only 2
times the original cube value.
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%)
The above is correct; if X redoubles, O should not beaver since 4.237 >
2.000. If O mistakenly beavers, X should drop the beaver, losing only 2
times the original cube value.
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%)
The above is correct; if X redoubles, O should not beaver since 4.107 >
2.000. If O mistakenly beavers, X should drop the beaver, losing only 2
times the original cube value.
Chris
- [Bug-gnubg] Re: Beaver bug,
Christopher D. Yep <=