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Subject: Re: perft records

Author: Uri Blass

Date: 07:08:40 09/06/04

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On September 06, 2004 at 09:48:17, Uri Blass wrote:

>On September 06, 2004 at 09:32:01, Reinhard Scharnagl wrote:
>
>>On September 06, 2004 at 09:21:36, Peter Fendrich wrote:
>>
>>>On September 06, 2004 at 09:06:06, Reinhard Scharnagl wrote:
>>>
>>>>On September 06, 2004 at 07:43:51, Peter Fendrich wrote:
>>>>
>>>>>What free programs have the fastest perft and what are the figures?
>>>>>Please, If you give figures also add processor, compiler and environment!
>>>>>
>>>>>I want to compare with a new concept that isn't coded yet...
>>>>>/Peter
>>>>
>>>>Hi Peter,
>>>>
>>>>see some of my (Smirf) results (still improved after measuring) at:
>>>>
>>>>a) without TT: [http://www.chessbox.de/Down/CRC_Test_03.txt]
>>>>b) with    TT: [http://www.chessbox.de/Down/CRC_Test_04.txt]
>>>>
>>>>Regards, Reinhard.
>>
>>>Hi Reinhard,
>>
>>Hi Peter,
>>
>>>I'm not sure how to read this. A few questions:
>>>It says break time 75 sec but in the table I find 166 sec. Is it 166 that
>>>I should count as the ply 7 result?
>>
>>Break time does mean that the test run will be stopped, when calculating a
>>single Perft ply has used that time or more.
>>
>>>That will get 3195901860/166 = 19252421 n/sec  Correct?
>>>Pretty fast!
>>>
>>>What environment/platform?
>>
>>(Pentium P4 2.79 GHz, MS VStudio C++ Compiler)
>>
>>>Finally, is this a MoveGen that you can use in normal play or do you have "perft
>>>tricks" in it (such as not doing MakeMove in the leaves and just count the moves
>>>in the move list)?
>>
>>I do not know what you are thinking of. You can see that I am also are counting
>>mates, which have to be detected first. But indeed, I have a move-generator
>>which produces fully informed moves (capture, e.p., check, double check,
>>mate ...). So using that hardly calculated information for to optimize perft is
>>no cheating. I think, that using a pseudolegal move generator is a trick
>>instead.
>
>I do not think that there is cheating there.
>It is impressive that you detect also number of mates.
>
>Movei does not detect checks or mates before it makes the move and it only
>detect checks and double checks even after making the move(the varaible
>checkingsquare is -1 when it is a double check).
>
>I suspect that it may be a good idea to add this information to my move
>generator if it can be done with a cheap price and the advantage is of course
>detecting mate in 1 faster and I will not need to search to see that the side to
>move can mate in 1(generating the moves of the side to move may be enough).
>
>Uri

I can add that it is probably not very expensive to detect mates in the move
generator(most moves can be detected fast as not checks) and the main problem is
to do it without bugs.

The main problem is probably after detecting a check to detect mate when your
attack tables are not updated to the mate board position but to the position one
ply earlier.

If I try something in the near future it will be probably only to detect checks
in move generator.

It may do movei even faster because it may be possible to use this detection to
do things faster in the real chess program when the target is not to calculate
perft.

Uri



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