Author: Alessandro Damiani
Date: 10:50:18 09/16/99
Go up one level in this thread
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
I agree with you, Peter. That is the idea of history heuristic. It should not
only be used when a cut-off occurs, but always when there is a best move.
And since everybody knows that there is no best move at a fail-low, the history
table should only be updated if
best>alpha
where best is the score of the best move.
Alessandro
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