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Subject: Re: Question on move ordering?

Author: Tom King

Date: 12:57:38 03/15/99

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On March 14, 1999 at 21:26:07, Robert Hyatt wrote:

>On March 14, 1999 at 18:02:51, William Bryant wrote:
>
>>I have a question on move ordering.
>>
>>The following list is how I think the order should be for determining the moves
>>to be searched.  I know that as I add PVS, NEGASCOUT, or other variations of
>>this theme to my search function, move ordering is important.  Any help with
>>this list in terms or order of importance or includion/exclusion would be
>>appreciated.
>>
>>1. Hash table move
>>2. PV move
>
>1/2 should be the same move, if you are searching the PV.
>
>
>>3. Killer move/moves
>>4. Promotions
>>5. Captures
>
>I don't separate promotions and captures.  I lump 'em together, but figure
>out which seems to improve the material balance the most.  IE I would play
>e8=Q if e8 is undefended, rather than a capture that captures less than a
>queen.  I use my SEE code to sort these moves.
>
>Also you do _not_ want to do killers before captures.  Captures are far more
>likely to refute the previous move since an exhaustive search leaves the moving
>piece 'hung' many times, or else leaves something else hung.
>
>

Bob's point is important. A long time ago, I did killers before captures, but it
was a big loser. Do your captures first! (This is actually mentioned in the
famous Chess4.5 paper, written in the 1970's, and still holds today).

Rgds,
Tom

>
>
>>6. All other moves.
>>
>>I realize that in some positions, some of these moves may end up being the same.
>> I.E. the hash table move and the PV move may be the same move.
>>
>>Thanks in advance.
>>
>>William
>>wbryant@ix.netcom.com



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