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Subject: Re: Does this position blow up your program?

Author: Uri Blass

Date: 15:25:13 12/23/02

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On December 23, 2002 at 17:33:26, Heiner Marxen wrote:

>On December 23, 2002 at 17:17:24, Robert Pope wrote:
>
>>On December 23, 2002 at 15:16:44, Mike Byrne wrote:
>>
>>>[d]R6R/3Q4/1Q4Q1/4Q3/2Q4Q/Q4Q2/pp1Q4/kBNN1KB1 w - - 0 1
>>>
>>>So far , every Palm program and Chess Tiger have fatal errors with this
>>>position.  Supossedly, this is the largest number of  possible legal number of
>>>moves, 218, available from one position in chess.  If you can prove this wrong,
>>>you'll go down in History.
>>>
>>>http://www.rescon.de/Compu/schachzahl2_e.html
>>
>>
>>Can I get some people to run perft numbers on this position?  Beaches correctly
>>says 218 legal moves, and finds xxx.  But then it gives these odd perft
>>statistics:
>>
>>perft 1: 218
>>perft 2: 99 ?????  Maybe because for many of the 218 moves, no response is
>>possible?
>>perft 3: 19073
>>perft 4: 85043
>
>Yes, Chest agrees completely:
>
>FEN: R6R/3Q4/1Q4Q1/4Q3/2Q4Q/Q4Q2/pp1Q4/kBNN1KB1 w - -
>Counting width of legal tree, 4 plies deep...
>Time (user) = 0.05 sec
>dep          #nodes     quot        sum nodes
>  0               1 [  0.000]               1
>  1             218 [218.000]             219
>  2              99 [  0.454]             318
>  3           19073 [192.657]           19391
>  4           85043 [  4.459]          104434
>
>Cheers,
>Heiner

Movei agree

perft 5 13,853,661(0.922 seconds)
perft 6 115,892,741(38.505 seconds)
perft 7 17,650,572,059(time 1182.761 seconds on 1000 mhz)

Yace checked the first 2 numbers and agreed about them.

Can somebody check that perft 7 is correct and calculates
perft 8 and perft 9?

Movei with branching factor of more than 30 may need many hours to calculate
perft 8, many days to calculate perft 9 and many months to calculate perft 10.

hash tables may help to calculate it faster but movei does not use hash tables
for this task.

Uri



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