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Subject: Re: To Bob: Crafty, move ordering with SEE

Author: Bas Hamstra

Date: 17:58:15 09/08/99

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I tried Bruces idea to play SEE<0 the very last. When I run the wac suite I
think it chokes on some positions. I like your scheme better, overall. I played
*all* captures before the killer(s), until yesterday. Doing the killers in
between is definitely a big win...

Another thing: I asked Bruce if it is a good idea to just skip nullmove the last
R ply. Some do that, I know at least 2 persons who do. Idea being to not allow
nullcuts on the basis of qsearch alone. So far I find it finds only very few wac
positions extra, with a worse branching factor. Also you do a lot more qnodes,
but less nodes in total.

I think it's not such a good idea, after all.


Regards,
Bas Hamstra.






Regards,
Bas Hamstra.

On September 07, 1999 at 10:45:37, Robert Hyatt wrote:

>On September 07, 1999 at 02:41:02, Alessandro Damiani wrote:
>
>>Hi Bob!
>>
>>Some time back you wrote here on CCC about the move ordering of Crafty. I don't
>>want to download all archive files, so I ask you now.
>>
>>If I remember it right, you use a SEE to order captures in the search. The
>>negative captures (SwapOff(.)<0) are placed after ALL the other moves?
>>
>>I thought, the "state of the art" is:
>>
>>1. transposition table move
>>2. positive captures (MVV/LVA)
>>3. killer 1
>>4. killer 2
>>5. counter move
>>6. rest of captures (MVV/LVA)
>>7. history moves
>>8. rest of moves (static ordering)
>>
>
>
>I do it like this:
>
>1. transposition move
>2. positive captures sorted by SEE score (best capture first)
>3. killer 1
>4. killer 2
>5. history moves (4)
>6. rest of moves, which just happens to do remaining captures first
>   since they were generated first.
>
>I don't do 'counter-move' as I didn't find any benefit at all.
>
>
>
>
>>I define "positive capture" this way:
>>Val(aggressor)<Val(victim) OR NOT Attacked(opponent, move.to).
>>
>>You said that the SEE gives you a better move ordering when the negative
>>captures are put after number 8?
>
>
>If I did, I wrote poorly...  The 'rest of the captures' come after the
>history moves, because they are still at the front of the move list, and
>after I give up on 'history moves' I just take the move list in order.
>
>
>
>>
>>Thank you!
>>
>>Alessandro (new E-mail address since today: adamiani@econophone.ch)



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