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Re: [Bug-gnubg] GNUBG gammon bug
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From: |
Ned Cross |
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Subject: |
Re: [Bug-gnubg] GNUBG gammon bug |
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Date: |
Sun, 20 Jul 2003 23:07:20 -0700 |
ummm, position attached.
black (O, 2 pts) vs. white (X, 4 pts)
(Match to 9)
Game number 5
Move number 87: X to play 12
GNU Backgammon Position ID:
/wMAADTbzQQEAA
Match ID :
UYkoASAAIAAA
+13-14-15-16-17-18------19-20-21-22-23-24-+
O:
black
|
X | O
|
O | O 2
points
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|
O | O
|
|
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O | O
|
|
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O | O
|
|
|
A |
v|
|BAR|
| 9 point
match
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|
|
|
|
|
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| |
X
|
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X | | X X X
X X | Rolled
12
| X
X | | X X X
X X | 4
points
+12-11-10--9--8--7-------6--5--4--3--2--1-+
X: white (Cube: 2)
Pip counts: O 35, X 86
* white moves 10/7
Cube analysis
2-ply cubeless
equity +0.509 (Money: +0.512)
0.764 0.000 0.000 - 0.236
0.017 0.000
Cubeful equities:
2-ply cubeful 100% speed [world
class]
1. No
double
+0.767
2. Double, pass
+1.000 ( +0.233)
3. Double,
take +0.686 (
-0.081)
Proper cube action: No redouble, take (25.8%)
Alert: bad move (
+0.000)
Rolled 12 (-0.004):
*
1. Rollout
10/7
Eq.: +0.849
0.763 0.000 0.000 -
0.237 0.000 0.000 CL +0.500 CF
+0.849
[0.002 0.000 0.000 - 0.002 0.360 0.003
CL 0.004 CF
+0.008]
Full cubeful rollout with
var.redn.
648 games, Mersenne
Twister dice gen. with seed 1177798656 and quasi-random
dice
Play: 2-ply cubeful 50%
speed
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 50%
speed
Different evaluations after
7 plies:
Play: 0-ply
cubeful
Cube: 0-ply
cubeful
2.
Rollout
5/2
Eq.: +0.835 ( -0.014)
0.764 0.000
0.000 - 0.236 0.000 0.000 CL +0.496 CF
+0.835
[0.001 0.000 0.000 - 0.001 0.452 0.014
CL 0.004 CF
+0.007]
Full cubeful rollout with
var.redn.
648 games, Mersenne
Twister dice gen. with seed 1177798656 and quasi-random
dice
Play: 2-ply cubeful 50%
speed
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 50%
speed
Different evaluations after
7 plies:
Play: 0-ply
cubeful
Cube: 0-ply
cubeful
3. Cubeful 2-ply 17/15
10/9
Eq.: +0.665 ( -0.183)
0.742 0.000
0.000 - 0.258 0.021 0.000
4. Cubeful
2-ply
17/14
Eq.: +0.664 ( -0.185)
0.740 0.000
0.000 - 0.260 0.018 0.000
5. Cubeful
2-ply 10/9
8/6
Eq.: +0.661 ( -0.188)
0.741 0.000
0.000 - 0.259 0.024 0.000
6. Cubeful
2-ply 17/15
5/4
Eq.: +0.653 ( -0.196)
0.735 0.000
0.000 - 0.265 0.017 0.000
Output generated Sun Jul 20 22:59:36
2003
by GNU Backgammon 0.14-devel 1.1177 030717 (Text Export version
1.47)
----- Original Message -----
Sent: Sunday, July 20, 2003 10:51 PM
Subject: Re: [Bug-gnubg] GNUBG gammon
bug
> Possibly related, I'm not sure...I just did a rollout today of the
attached
> position, and strangely GNU reported a 0.0% chance of losing a
gammon.
> GNU's 2-ply eval showed gammon percentages around 2-3% for each
of the top
> two plays, as did Snowie 4 evals and rollouts.
>
> Interestingly enough, I originally decided to rollout the position
because
> GNU 2-ply eval listed 5/2 as the top move (10/7 as second best,
but a
> significant error), while Snowie 4 listed 10/7 as best, with 5/2
far down
> the list. Performing a rollout with both bots gave the
result that they
> BOTH changed their minds...Snowie rollout (2-ply with
3-ply cube, 324 trials
> with VR), preferred 5/2 and GNU rollout preferred
10/7.
>
> I don't know if the gammon percentages would make a
difference in GNU's
> choice of "best move", but it seems like a problem
in either the rollouts or
> the reporting of rollout results.
>
> Ned
>
> ----- Original Message -----
> From: "Jim
Segrave" <address@hidden>
> To:
<address@hidden>
> Cc:
<address@hidden>
> Sent:
Sunday, July 20, 2003 3:57 PM
> Subject: Re: [Bug-gnubg] GNUBG gammon
bug
> > I'm very glad you raised this, it caused me to find and fix a
rather
> > stupid bug in the new rollout code. Having fixed it, the
answer is:
> >
>