Author: Alvaro Jose Povoa Cardoso
Date: 15:02:46 07/04/01
Some time ago I saw here a discussion about adjusting mate scores.
Dr. Hyatt said we should do so only if they were exact scores.
Others have said we could also adjust upper and lower bounds mate scores.
Can some one please elaborate a 'complete' explanation on this?
In my checkers program if I adjust every (exact, upper or lower) mate score I
can get wrong mate positions from hash.
For example: I can get a position that says white wins in 50 moves (!!!) but in
reality it loses in 3 moves.
On the other hand if I adjust only exact scores those errors disappear, but
another one comes in.
I get mate in 15, then mate in 14, then mate in 13, then mate in 15 again, then
mate in 14, then mate in 13...
I wonder how my program can make progress towards a win with these scores.
Are these errors correlated?
As an example here is the output of a (portuguese) checkers game in wich I
adjust only exact scores:
White: 20 ply Black: 20 ply IDS_Step = 2
Nº Move Score Nodes
1W 8-19 31978 39,680,403
2B 3x13 31979 11,938,167
3W 19-14 31980 7,539,580
4B 18x11 31981 88,312
5W 9x18 31982 20
6B 25x14 31983 18
7W 5-10 31984 90,491
8B 14x5 31985 16
9W 1x14x4 31986 113
10B 17-13 31987 60,257
11W 4-14 31988 1,281
12B 13-9 31989 1,485
13W 14-32 31990 514
14B 31-27 31991 300
15W 32-14 31992 84
16B 27-22 31993 84
17W 14-1 31994 130
18B 22-18 31995 59
19W 1-32 31996 78
20B 9-5 31995 238
21W 32x1 31996 55
22B 18-13 31997 6
23W 1-14 31998 24
24B 13-9 31997 54
25W 14-19 31998 32
26B 9-5 31999 2
27W 19x1 32000 2
Totals -> 59,401,805
If I adjust every mate score the progress towards a win is perfect, but as I
said before I can get wrong mate positions from hash.
Can someone please help with an explanation (as complete as possible) on the
matter of adjusting mate scores?
Thank you all,
Alvaro Cardoso
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