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Subject: Re: Question about the nps difference between MiniMax and AB

Author: Mathieu Pagé

Date: 06:12:39 03/05/04

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On March 04, 2004 at 15:25:53, Dann Corbit wrote:

>On March 04, 2004 at 15:16:43, Mathieu Pagé wrote:
>
>>Hi,
>>
>>I've just change my minimax algorithm for an AB one. (Yes I know i should have
>>done this long long time ago, but i did want to keep it simple until it could
>>play a complete game and understand _all_ the chess rules).
>>
>>As expected my engines can search deeper (3-4 more plys) than the old version in
>>the same time, but the NPS drop dramatically, going from 3.6M nodes/s to a
>>little bit over 2M nodes/s. It's about 44 % decrease.
>>
>>I think it is normal that the nps of Minimax was greater then AB's one because
>>in AB lot of move are generated, but not searched (so they are not add to the
>>number of nodes)
>>
>>but i think that going from 3.6M to 2M is a big difference.
>>
>>Is this behavior normal or did I put an unusual overhead in my algorithm (For
>>now, i have carefully revised my code and can not see what it is) ?
>>
>>TIA     :)
>>
>>Mathieu Pagé
>
>How do you count nodes?

Each call to AB, I count it as a node. (I have no quiescence or other fancy
things)






>Does your perft calculation give a different rate now?

No, my perft is as fast as it was (over 4 millions nodes per seconds)





>I suspect the difference is that you spend more time in the search and less time
>in the move generator.  But that is only a guess.

I guess you mean more time in the move generation less in the search. did you ?
Note that i still have no ordering except a primitive LVA (without MVV ??) move
ordering is the next step on my TODO

Mathieu P.



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