You may turn on a log of all games in a rollout. If you do so you
observe that the error when using the cli is caused by gnubg not
doubling on the first turn as it should. Later doubles for both
players are made correctly (not relevant for this position) and
anything else you may think of is seemingly correct. Is it possible
that the rollout position is initialized so that gnubg skips the
doubling decision?
Christian.
On 8/21/06, [EMAIL PROTECTED]
<[EMAIL PROTECTED]> wrote:
Hi all, this bug in in the bug-tracker on gnubg.org, but it looks
so huge to me that it's maybe worth checking if anybody is having
a look at it.
GNU Backgammon Position ID: GwAAYAMAAAAAAA
Match ID : cAkFAAAAAAAA
+24-23-22-21-20-19------18-17-16-15-14-13-+ O: gnubg
OOO | O O | | | 0 points
OO | O O | | |
OO | | | |
OO | | | |
OO | | | |
| |BAR| |v (Cube: 1)
XX | | | |
XX | | | |
XX | | | |
XX | X X | | | Rolled 21
XXX | X X | | | 0 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: MaX
A hint says :
1. Cubeful 2-ply 2/off 1/off Eq.: +0.722
86.1% 0.0% 0.0% - 13.9% 0.0% 0.0%
2-ply cubeful prune [world class]
2. Cubeful 2-ply 2/1 2/off Eq.: -1.000 ( -1.722)
14.4% 0.0% 0.0% - 85.6% 0.0% 0.0%
2-ply cubeful prune [world class]
Notice that after 2/1 2/off, player 1 will double out player 2
(hence the equity of -1.000).
Now selecting the two moves and doing a rollout we get the same result
(equities of +0.722 and -1.000) in the GUI version, but a different
result in the command-line (CLI) version : it gives equities of +0.722
and -0.713. As pointed out by the person that reported the bug (Philippe
Michel), -0.713 is the cubeless equity.
It is not a coincidence, since the same behavior appears for the following
position :
GNU Backgammon Position ID: GwAAYAsAAAAAAA
Match ID : cAkFAAAAAAAA
+24-23-22-21-20-19------18-17-16-15-14-13-+ O: gnubg
OOO | O O | | | 0 points
OO | O O | | |
OO | | | |
OO | | | |
OO | | | |
| |BAR| |v (Cube: 1)
XX | | | |
XX | | | |
XX | | | |
XX | X X | | | Rolled 21
XX | X X X | | | 0 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: MaX
Here, no matter the move, player 1 is gonna double out player 2 next turn.
While GUI version correctly shows equities equal to -1.000 after a rollout,
CLI version shows cubeless equities ...
(MaX) hint
1. Cubeful 2-ply 2/off 1/off Eq.: -1.000
12.0% 0.0% 0.0% - 88.0% 0.0% 0.0%
2-ply cubeful prune [world class]
2. Cubeful 2-ply 3/off Eq.: -1.000 ( +0.000)
12.0% 0.0% 0.0% - 88.0% 0.0% 0.0%
2-ply cubeful prune [world class]
3. Cubeful 2-ply 2/1 2/off Eq.: -1.000 ( +0.000)
9.6% 0.0% 0.0% - 90.4% 0.0% 0.0%
2-ply cubeful prune [world class]
4. Cubeful 2-ply 3/1 2/1 Eq.: -1.000 ( +0.000)
0.0% 0.0% 0.0% - 100.0% 0.0% 0.0%
2-ply cubeful prune [world class]
(MaX) rollout =1 =2 =3 =4
1. Rollout 2/off 1/off Eq.: -0.761
12.0% 0.0% 0.0% - 88.0% 0.0% 0.0% CL -0.761 CF -0.761
[ 0.0% 0.0% 0.0% - 0.0% 0.0% 0.0% CL 0.000 CF 0.000]
Truncated cubeful rollout (depth 11) with var.redn.
648 games, Mersenne Twister dice gen. with seed 1036242101 and
quasi-ran
dom dice
Stop when best play is enough JSDs ahead: limit 1.96 (min. 144
games)
Play: world class 2-ply cubeful prune [world class]
keep the first 0 0-ply moves and up to 8 more moves within equity
0.16
Skip pruning for 1-ply moves.
Cube: 2-ply cubeful prune [world class]
2. Rollout 3/off Eq.: -0.761 ( +0.000)
12.0% 0.0% 0.0% - 88.0% 0.0% 0.0% CL -0.761 CF -0.761
[ 0.0% 0.0% 0.0% - 0.0% 0.0% 0.0% CL 0.000 CF 0.000]
Truncated cubeful rollout (depth 11) with var.redn.
648 games, Mersenne Twister dice gen. with seed 1036242101 and
quasi-ran
dom dice
Stop when best play is enough JSDs ahead: limit 1.96 (min. 144
games)
Play: world class 2-ply cubeful prune [world class]
keep the first 0 0-ply moves and up to 8 more moves within equity
0.16
Skip pruning for 1-ply moves.
Cube: 2-ply cubeful prune [world class]
3. Rollout 2/1 2/off Eq.: -0.809 ( -0.048)
9.6% 0.0% 0.0% - 90.4% 0.0% 0.0% CL -0.809 CF -0.809
[ 0.0% 0.0% 0.0% - 0.0% 0.0% 0.0% CL 0.000 CF 0.000]
Truncated cubeful rollout (depth 11) with var.redn.
144 games, Mersenne Twister dice gen. with seed 1036242101 and
quasi-ran
dom dice
Stop when best play is enough JSDs ahead: limit 1.96 (min. 144
games)
Play: world class 2-ply cubeful prune [world class]
keep the first 0 0-ply moves and up to 8 more moves within equity
0.16
Skip pruning for 1-ply moves.
Cube: 2-ply cubeful prune [world class]
4. Rollout 3/1 2/1 Eq.: -1.000 ( -0.239)
0.0% 0.0% 0.0% - 100.0% 0.0% 0.0% CL -1.000 CF -1.000
[ 0.0% 0.0% 0.0% - 0.0% 0.0% 0.0% CL 0.000 CF 0.000]
Truncated cubeful rollout (depth 11) with var.redn.
144 games, Mersenne Twister dice gen. with seed 1036242101 and
quasi-ran
dom dice
Stop when best play is enough JSDs ahead: limit 1.96 (min. 144
games)
Play: world class 2-ply cubeful prune [world class]
keep the first 0 0-ply moves and up to 8 more moves within equity
0.16
Skip pruning for 1-ply moves.
Cube: 2-ply cubeful prune [world class]
Pretty scary to me ...
MaX
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