On Tue, Jun 5, 2012 at 12:33 AM, Philippe Michel
<address@hidden> wrote:
The benchmark database for the crashed positions seems seriously corrupted.
Offhand, it seems that many positions with significant backgammons in play are very innacurate.
For instance :
#R HLDHABAADEAEAAAAAAAA 0.999958 0.696718 0.000878771 0 0
#R HHDHACAADEAEAAAAAAAA 0.999994 0.695403 0.00295781 0 0
#R LLJLCAACDAAEAAAAAAAA 0.999805 0.970848 0 0 0
#R LLJLABEADAAEAAAAAAAA 0.999858 0.969998 0 0 0
#R LLJLACCADAAEAAAAAAAA 0.999771 0.978238 0.00154321 0 0
#R LLJLCAAECIAEAAAAAAAA 1 0.444444 0 0 0
#R LLJLCACACBAEAAAAAAAA 1 0.666667 0 0 0
m AEAAAAOMGOICAANAAAAA 5 4 LLJLCAAECIAEAAAAAAAA -1.444444 LLJLCACACBAEAAAAAAAA 0.222223 HLDHABAADEAEAAAAAAAA 0.253066 HHDHACAADEAEAAAAAAAA 0.253902372 LLJLABEADAAEAAAAAAAA 0.525268 LLJLCAACDAAEAAAAAAAA 0.52601 LLJLACCADAAEAAAAAAAA 0.534875
The position is :
+24-23-22-21-20-19------18-17-16-15-14-13-+ O: GNUbg
OOO | X X O | | | 0 points
OOO | X | | |
OOO | | | |
OOO | | | |
OO | | | |
| |BAR| |v
| | | |
| | | |
| X X | | |
| X X X X | | | Rolled 54
| X X X X X | | X | 0 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: You
What ID corresponds to what move doesn't really matter : it is obvious thax X loses a lot of backgammons, and more than 44, 67 or 70% gammons.
The position is worth about -2.96 (cubeless), not -1.44, the possible errors are small, not random 0.2 or 0.5 blunders.
This is a rather extreme case, but I think the aggregate effect is important enough to significantly impair the usefulness of this benchmark.
I didn't look at the other databases. It seems the were done later, with a more recent version of the rollout tool.
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