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Subject: Re: perft results (how accurate is accurate enough ?)

Author: Heiner Marxen

Date: 15:16:25 09/23/04

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On September 23, 2004 at 17:44:25, Andreas Guettinger wrote:

>On September 23, 2004 at 16:58:33, Roman Hartmann wrote:
>
>>hello all,
>>
>>while testing my move generator (10x12 array, only legal moves) and comparing
>>the perft result from Crafty and my own results I noticed that my results differ
>>for some positions a bit. As the results start to differ only at some depth it's
>>not that easy to track this bug. Although I'm quite certain that the problem is
>>somehow related to EP-moves I wasn't able to solve this riddle yet.
>>
>>By searching the web I found some websites with perft results from other chess
>>engines with numbers even more off than the results from my move generator.
>>
>>some results -total nodes- from my move generator (proper Results from Crafty):
>>rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
>>perft 4: 20603 ok
>>perft 5: 5072212 ok
>
>perft 5: nodes: 4865609
>
>This is the starting position, right?
>Your Crafty version must be broken.

Most probably he sums over all depths up to the specified one,
but excludes the initial position.
Here is the data from Chest:

dep          #nodes     quot        sum nodes
  0               1 [  0.000]               1
  1              20 [ 20.000]              21
  2             400 [ 20.000]             421
  3            8902 [ 22.255]            9323
  4          197281 [ 22.161]          206604
  5         4865609 [ 24.663]         5072213


>regards
>Andy

Cheers,
Heiner



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