Author: Daniel Clausen
Date: 07:14:51 04/18/03
Go up one level in this thread
On April 18, 2003 at 09:55:13, Geoff wrote:
>Hi
>
>I have just started my first few tentative steps of trying to figure out how
>to write a computer chess program. Its going fairly well but I hit a slight
>snag. I have been starting off by reading and using Tom Kerrigan's excellent
>program. I have begun by using a simple Negamax search that looks at every
>possible node, I have added a counter for the number of nodes searched.
>
>When I print this out for a 1 ply search from the normal start position I
>get the expected
>
>1 ply = 21 I.E root node + 20 white moves (16 pawn moves and 4
>knight moves)
>
>however, my program gives me
>
> 2 ply = 421
>
> 3 ply = 9,323
>
> 4 ply = 206,604
ply 0 1 (total 1)
ply 1 20 (total 21)
ply 2 400 (total 421)
ply 3 8'902 (total 9'323)
ply 4 197'281 (total 206'604)
>I suspect my figures for ply's 2 to 4 are wrong, but it is dificult to prove
>one way or another ?
Your numbers are correct. You can verify such numbers with programs which
support the 'perft <ply>' command, e.g Crafty.
Btw: A good position to test your move generator is this one (also called
'KiwiPete-position' - at least by me :)
[D] r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq -
It's a good test position since it involves many things like ep, castling etc.
The number of legal positions for ply 1 and so on are: 48; 2,039; 97,862;
4,085,603; 193,690,690; 8,031,647,685 ('finger kiwipete' in the ICC shows this
information too)
Good luck! :)
Sargon
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