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Subject: Re: Mathematical impossibilities regarding Deep Blue statements by Bob

Author: Uri Blass

Date: 11:47:42 01/30/02

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On January 30, 2002 at 14:43:19, Dann Corbit wrote:

>On January 30, 2002 at 14:39:04, Uri Blass wrote:
>>On January 30, 2002 at 14:15:32, Dann Corbit wrote:
>>>On January 30, 2002 at 14:00:32, David Rasmussen wrote:
>>>
>>>>On January 30, 2002 at 09:43:49, Vincent Diepeveen wrote:
>>>>
>>>>I don't know anything about what Bob has stated, but I agree that 18 ply
>>>>fullwidth was/is impossible, even with 200 Mn/s.
>>>>
>>>>Please email me how you do singular extensions, Vincent. :)
>>>
>>>I've done 18 ply searches with a PC.  What makes you think it is impossible for
>>>a machine that can peak at one billion nodes per second?
>>>
>>>They did not use null move, but neither did they blindly search the whole tree.
>>
>>
>>I suggest that you try to do with Crafty without null move pruning 18 ply search
>>in the same positions that deeper blue was supposed to search 18 plies.
>>
>>Note that Crafty without null move pruning does not search all the tree.
>>
>>I am interested to know how many nodes do you need.
>>
>>you can claim that they had more hash tables so try to search 16 plies and guess
>>the number of relevant nodes based on the branching factor.
>>
>>If you think that deeper blue used more hash tables then please search 16 plies
>>twice when the hash tables is twice bigger in the second time(I think that
>>doubling the hash tables from 128 Mbytes to 256 Mbytes is not going to change
>>the time significantly)
>>
>>If Crafty without null move pruning cannot search 18 plies in similiar number of
>>nodes then I do not believe that deeper blue that is supposed to use more
>>extensions could do it.
>
>Null move is not the only way to reduce the tree.  Did you know that Rebel did
>not use null move for some time?  How do you imagine that it remained
>competitive?  Obviously, by pruning the tree in some other way.

Yes but I understood that Deeper blue did not use pruning except maybe qsearch
and most of the nodes in the tree are not qsearch nodes.

Uri



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