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Subject: Re: Bitboard VS array board ,speed difference in movegen()

Author: TEERAPONG TOVIRAT

Date: 09:17:48 02/28/01

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>You will run this to test to speed of your movegen and makemove?
>That's how I understood your original message.

Actually,my current program is checkers one. In former version,
I use single array board representation. After I read Amy source
code,I understand how bitboard works. I heard many people said
bitboard can generate move faster in chess. In checkers,
some facts are no nullmove,no killers,no PVS ,no SEE etc..and
very simple eval() and  plain AB function with hash table.
So,I think if I can improve movegen() speed,my program
will be stronger. Then, the project start ,I wrote a new checkers
program based on bitboard ,modified from Amy. The result was
quite dissapointed it's slower. You may look at what Dr.Hyatt
commented. Amy bitboard always updates attack_to,attack_fr
informations in (un)makemove()s. If only 2 movegen()s were
compared, bitboard is slightly faster. But if test it in combination
with (un)makemove()s,it becomes slower in proportion to the
ratio of (un)makemove()s. So,this is my original question what
is the optimum ratio between them.
Is it acceptable to use branching factor ?
How other people test these problems?
I don't know really. I'm not a great programmer :)
Now,I focus of movegen() in Crafty. I plan to modify it into my
program. I still have some hope with bitboard.

>I don't understand what you mean when you say this:

>"And call it recursively to count number of visiting nodes then compare
>with our real search()."
I remember when I experimented about branching factor myself.
I have some problems ie.it varies from ply to ply ,from position to position
and from game to game. Please remember we didn't talk how the figure
4 are  from. Perhaps,the branching factor is 4 in some situations and
less(more) than 4 in some situations. So,a perfect test,IMHO, should
have approximately the same nodes as normal search() does.
Perhaps,I'm too anxious about this. You may call me a Mr.perfectionist.


>Count which nodes? Isn't it obvious how many you will visit?
>What will you use that number for? Am I still missing something?

Just to convince you  that  your figure is too high.

I think now we have reached some agreement.
I'm really happy for your interest to my post. I cannot find
anyone  surrounding me who  interested in computer  chess,
so, I think CCC is a wonderful place. CCC lets me express my idea
and gives me some interesting ideas from other people.
Now,it's late at night again... :)

Teerapong




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