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

Author: Dann Corbit

Date: 11:45:20 01/30/02

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On January 30, 2002 at 14:25:18, David Rasmussen 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.
>
>It is of course possible to search 18 ply. Chezzz searches 35 ply in fine70 in 1
>second :)
>
>But in a normal middlegame situation with a high branching factor, I don't
>believe it, even if you have 200 Mn/s. As far as I understood, DB _did_ pretty
>much blindly search "the whole" (of course they used alpha-beta pruning) tree.

Why do you understand that?  I have talked to Murray Campbell and am very sure
that it is not the case.  On what do you base your understanding?

>They had extensions, but as far as I know, no forward pruning of any kind. I
>might be wrong.

I don't know what kind of pruning they used.  But use it they did.  I also know
that the search algorithm changes in some way after 30 seconds.



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