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Re: [Bug-gnubg] Gnu 2ply seems too optimistic
From: |
Albert Silver |
Subject: |
Re: [Bug-gnubg] Gnu 2ply seems too optimistic |
Date: |
Wed, 8 Nov 2006 11:08:38 -0300 |
There are other areas where it is much much worse. For example
evaluating cube situations in containment games, I have positions
(several), where the 2-ply might say No Double/take, and a rollout
will say Too Good to Double/Pass.
GNU Backgammon Position ID: 73sAAAyYM7RCBQ
Match ID : UQkAAHAAGAAA
+13-14-15-16-17-18------19-20-21-22-23-24-+ O: V72222
| X X X | | X X X O O O | 7 points
| X | | O O O |
| | | O O O |
| | | O O O |
| | | O |
v| |BAR| |
| | | |
| | | |
| | | X |
| X | | X X O | On roll
| X X | | X X O | 3 points
+12-11-10--9--8--7-------6--5--4--3--2--1-+ X: AlmostDecent (Cube: 2)
Cube analysis
2-ply cubeless equity +0.4984
71.86% 17.30% 0.09% - 28.14% 11.22% 0.05%
Cubeful equities:
1. No double +0.8127
2. Double, pass +1.0000 ( +0.1873)
3. Double, take +0.8073 ( -0.0054)
Proper cube action: No redouble, take (2.8%)
Cube analysis
Rollout cubeless equity +0.6281
Cubeful equities:
1. No double +1.1187
2. Double, take +1.2742 ( +0.1555)
3. Double, pass +1.0000 ( -0.1187)
Proper cube action: Too good to redouble, pass (43.3%)
Rollout details:
Player AlmostDecent owns 2-cube:
76.11% 20.29% 0.37% - 23.89% 10.02% 0.05% CL +0.6281 CF +1.1187
[ 0.16% 0.24% 0.05% - 0.16% 0.13% 0.01% CL 0.0052 CF 0.0124]
Player V72222 owns 4-cube:
77.65% 22.01% 0.64% - 22.35% 9.88% 0.05% CL +1.3608 CF +1.2742
[ 0.17% 0.30% 0.06% - 0.17% 0.15% 0.02% CL 0.0111 CF 0.0154]
Full cubeful rollout with var.redn.
1298 games, Mersenne Twister dice gen. with seed 1038057470 and
quasi-random dice
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]
Albert
On 11/8/06, address@hidden
<address@hidden> wrote:
Mochy wrote:
>Recently I found 3 positions where Gnu 2ply evaluate the
>equity too optimistic.After the rollout or in Snowie evaluation (and
>Rollout) , Those are actually huge pass.
>Not only 2ply, 4ply also make similar mistakes.
>
>I dont know if it is because of new build or not.
>Any comments are welcome.
>
>Here are 3 positions (Position ID / Match ID)
>ZtvAAWBjN4MIDA / cAmgAQAAAAAA
>bFsIOEhxOwcDIA / MAGgAVAAMAAA
>xs7BAURwb4OFAA / MAHgADAAAAAA
>
>Mochizuki Masayuki (mochy)
>address@hidden
Hi Mochy,
as stated by others, a bug has been introduced in some important evaluation
code
affecting evaluation of positions with a player having 2 men on the bar.
I checked your poistions with the latest available source code and they all
are
pass at 2-ply world-class.
I'm currently unable to put a new Win distrib (or just the new executables)
on
the www.gnubg.org site : due to a local network problem, I'm unable to do
anye
external FTP.
I can mail you the new executables (1.2Mb) so you can check they behave "as
expected". Let me know if you're interested.
MaX.
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