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Subject: Re: 0x88 fast move generation

Author: Dann Corbit

Date: 15:24:49 01/17/04

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On January 17, 2004 at 18:03:24, Jan wrote:

>>From the opening position, how many times per second can you call your move generator?
>When writing this reply, i have no access to my program to write the precise
>number which i dont remember, but its between 1500000-2000000 times per second.
>I think that's really slow on my Athlon 1800, so the question is:how many calls
>will I really need when I do for example 9 or 10ply search?

By brute force mini-max, the count is enormous.  By alpha-beta it becomes
reasonable (square root of 'enormous' is much more manageable).   Hash tables
and better move ordering will save another 50%.  Then null move will be another
giant help.  Then some little things like IID will save you 1/3 more.

from the distributed perft page

http://www.albert.nu/default.asp?sub=programs/default.asp?sub=dperft/main.htm

1 20
2 400
3 8902
4 197281
5 4865609
6 119060324
7 3195901860
8 84998978956
9 2439530234167
10 69352859712417
11 2097651003696806

sqrt(2439530234167) = 1561899.5595642505974616326987721
so with perfect move ordering, you can reach 9 ply with only 1.6 million nodes.
About one second for your move generator.

>>Concentrate on making a working program first, even if it is slow and weak.
>I wrote that i'm new to chess programming but I have already finished my first
>chess program, with elo somewhere around 1650 tested on real players. In the end
>I found it's too slow to try to implement some more complicated algorithms, so
>now I started writing another program, trying to avoid all those bottlenecks,
>making sure that i wont have to make drastic changes in those often used
>algorithms like check and move generation later on.

Make the algorithms as clear an simple as possible.  Alpha-beta is about 30
lines or so.




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