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Subject: Re: What is the average nodes per second for minimax?

Author: blass uri

Date: 23:22:16 06/24/00

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On June 24, 2000 at 21:40:19, leonid wrote:

>On June 24, 2000 at 15:11:46, blass uri wrote:
>
>>On June 24, 2000 at 15:02:09, blass uri wrote:
>>
>><snipped>
>>>>Alpha-beta can give you very often as much as 15 moves of equal value in the
>>>>first half of usual game. I speak all the time about what I call "positional
>>>>logic".
>>>
>>>Alpha beta never gives you more than one move with a value and other moves that
>>>you know that they are not better and you have no idea if they are equal or
>>>worse.
>>
>>To be more exact alpha beta is a function that givees you a number (alpha if the
>>evaluation of the position after search is worse than alpha,beta if the
>>evaluation after search is bigger than beta and a score between alpha and beta
>>in other cases.
>>
>>
>>If the evaluation of Na3 after search is 0.00 you are not intereted in the exact
>>value of e4 if it is not better than 0.00 and your calculation will give 0.00
>>even if e4 is losing material  so you will have no way to know if e4 is losing
>>or leads to an equal position.
>>
>>Uri
>
>Ura, probably all confusion is about the ply number. I speak about upper ply.
>Ply where you are forced to see all the moves. It is the place where multiple
>moves you can have to chose later.
>
>Leonid.

I understand that you calculate only material evaluation for all the legal moves
and if the result is equal you calculate decide which move to search first by
positional score so you can avoid 1.Na3 and play 1.e4 because the positional
evaluation(not material evaluation) of 1.e4 is better than the positional
evaluation of 1.Na3.

This is better than only material evaluation but still worse than
doing the things in one step because if a move is losing something positional
and you do not see it in the first ply you will never see it if you do not see
that it loses material.

I do not see the reason to do 2 steps when you can calculate it in one step.

Uri



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