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Subject: Re: History Heuristic

Author: Robert Hyatt

Date: 11:57:13 03/16/04

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On March 16, 2004 at 11:12:34, Renze Steenhuisen wrote:

>On March 16, 2004 at 09:51:00, Pat King wrote:
>
>>On March 16, 2004 at 04:41:40, Renze Steenhuisen wrote:
>>
>>>
>>>Hi all!
>>>
>>>I did some measurements on my move-ordering, and it seems that the positive
>>>effect of the History Heuristic wears of with increasing search depth? Is this
>>>observed by others as well or am I doing something awfully wrong here...
>>>
>>>
>>>History Heuristic:
>>>
>>>    int table[64][64];
>>>
>>>    every time the 'best move' was found (either fail-high or all moves
>>>    searched)
>>
>>"All moves searched" = fail low = move ordering doesn't matter here. I think you
>>ought only store fail-highs in the history table. It will lose its effectiveness
>>more slowly that way.
>
>Have you had any success with this way of applying the HH or is it just a
>suggestion? It doesn't seem to work here, or I am not counting my move right!
>
>Cheers!


The only time you should update the history counter is when you either fail
high, or you back up a value that is > alpha.  IE at PV and CUT nodes, but
_never_ at an ALL node...

Any other way will fail.



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