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Subject: Re: About history and aging it

Author: Mikael Bäckman

Date: 13:28:30 03/17/04

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On March 17, 2004 at 16:22:42, Dann Corbit wrote:

>On March 17, 2004 at 16:14:40, Mikael Bäckman wrote:
>>
>>Hi,
>>
>>I ran some tests with history and different methods of aging it, as discussed in
>>this thread:
>>
>>http://www.talkchess.com/forums/1/message.html?354812
>>
>>I picked 15 test positions from this years Linares tournament. 10 positions are
>>from move 20 and 5 from move 40. I didn't study the positions much before
>>selecting them.
>>
>>I used 90 seconds per position as I didn't know how deep I could search without
>>spending days on this... First I ran a test without historytables, to get a
>>depth to compare the other tests to. Most of the depths were completed in 20-60
>>seconds. Perhaps a bit shallow, but it gives an idea of the performance.
>>
>>I use a side-piece-to historytable or history[side][piece][to] and I use at most
>>8 history moves at a node. After that I try the moves in the order they are
>>generated.
>>
>>
>>Test1 = No History
>>Test2 = History
>>Test3 = History - root aging
>>Test4 = History - age as soon as a history score gets larger than 10000.
>>Test5 = Same as 2 but with pawnmoves generated after all other moves. Included
>>this for fun, but it seems to work best. :)
>>
>>Aging was done by dividing the values in the history tables with 8.
>>Nodecounts are in thousands.
>>
>>Pos   D   Test1   Test2   Test3   Test4   Test5
>>--------------------------------------------------
>>01   12   27960   22044   21481   21923   21954
>>02   12   37488   31165   31706   25631   26492
>>03   10   34388   24471   24652   29455   24225
>>04   12   25099   21307   23497   20555   23460
>>05   13   30665   22026   22288   22156   21798
>>06   10   16141   12861   13447   13050   13576
>>07   14   44136   32362   31157   32776   32958
>>08   14   39848   38378   39681   38337   28706
>>09   11   31083   21410   24811   25470   25403
>>10   12   38152   29568   28020   29394   25669
>>11   13   29184   25017   27149   24854   23437
>>12   13   52650   27674   24784   26427   25901
>>13   14   58192   38986   41854   37978   41428
>>14   13   50823   45372   41400   41283   45473
>>15   13   63876   33226   32296   33651   32625
>>--------------------------------------------------
>>         579685  425867  428223  422940  413105
>>         (136%)  (100%)  (101%)   (99%)   (97%)
>>
>
>A 40% improvement for history heuristic is well above average improvement, I
>think.
>
>Did you have hashing and other move ordering techniques in play?  I think not.
>If you have hashing operational, I would expect less than 25% improvement.


Yes.
I sort moves by:

1. Hash
2. Good captures
3. Equal captures
4. Killers
5. History
6. Losing captures

I use SEE for captures.


>What happens when you have all of your move ordering techqniques in use and then
>you change only the history heuristic?

All moveordering techniques were in use. The above happens. :)

/Mikael




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