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Subject: Re: Move ordering question

Author: Andrew Williams

Date: 10:34:18 01/04/02

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On January 04, 2002 at 10:33:27, John Coffey wrote:

>On January 04, 2002 at 10:14:17, Severi Salminen wrote:
>
>>>There has been some confusion in my mind for years
>>>about move ordering.  I know that good move ordering will reduce the size of
>>>the tree.  How important is it to get all the moves in the best order as
>>>oppose to just starting with the best candidate?
>>
>>The optimal solution is a movegenerator that allways generated the best move.
>>But since that is quite impossible it is best to try to generate only those
>>moves that are likely needed and get a cutoff as fast as possible. 1. try the
>>hash move and don't generate others. 2.  generate captures and try the good
>>ones. 3. try killers. 4. generate the rest and order them by history values. 5.
>>try the bad captures. In each step try to do as little as possible, generate
>>only the moves you need and do it fast. So if you get a cutoff with a hash move,
>>you really don't need to know _anything_ about the rest of the possible moves.
>>
>>Severi
>
>How many programs actually do this and how many generate the entire move list?
>
>John Coffey

I generate all mine at once. I've tried in the past generating them in two
stages (captures+promotions then non-captures), but I never got any huge
improvement and dropped it in favour of simplicity.

Andrew



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