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Subject: Re: What is the History table?

Author: Peter Fendrich

Date: 09:07:57 09/17/99

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On September 16, 1999 at 22:52:42, Robert Hyatt wrote:

>On September 16, 1999 at 12:46:20, Peter Fendrich wrote:
>
>>On September 16, 1999 at 05:18:42, Bas Hamstra wrote:
>>
>>- snip -
>>
>>>History:
>>>
>>>(I never used it)
>>>
>>>A table of counters, used for movesorting. You use a table History[From][To] to
>>>keep track of the number of beta cutoffs for each move [From][To]. And use that
>>>to improve the probability of a cutoff (as you do with killers). If you already
>>>use more than 1 killer I have the impression History doesn't give much extra.
>>>
>>I don't agree with you here. My implementation of killer table only has effect
>>on local parts of the tree. For each new path the killer moves are cleared. The
>>history table is covering all of the tree and really improves move ordering in
>>some nodes. Normally there is no big overlap betwee the two.
>>//Peter
>
>
>First, don't clear the killers, ever.  Second, use them before generating any
>moves, after making sure each is a valid move in the current position...

Well, I don't clear the killer but the counter is set to 0 in the beginning of
each new ply...
//Peter



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