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

Author: Dann Corbit

Date: 11:36:04 01/31/02

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On January 31, 2002 at 14:31:38, David Rasmussen wrote:

>On January 31, 2002 at 13:13:57, Dann Corbit wrote:
>
>>On January 31, 2002 at 06:58:28, David Rasmussen wrote:
>>[snip]
>>>>Just like "ply" means 20 different things to 20 different programmers.  Even
>>>>"nodes" does not always mean the same thing.
>>>>
>>>
>>>Agree with you on nodes, but ply? Ply is pretty well defined, I think.
>>
>>For sure it is not.  In fact, even when we agree, we disagree.  Every single
>>chess program will have a tree of a different shape.  So even when we count
>>plies the same way, the actual search can be incredibly different (with the
>>number of nodes visited differing by several orders of magnitude).  Compare, for
>>instance, Mchess with Goliath.
>>
>>Junior [for instance] does not count plies the same way as other programs.
>>
>>Ply is ill defined.  In fact, I think it is actually impossible to define it
>>accuracy, except in the brute force sense.  And absolutely nobody exhausts a ply
>>when doing chess games with an engine.
>>[snip]
>
>That is bull. A ply is a half move and that is that. What you are talking about
>is: what does it mean when we say a program searches 8 ply? Of course if that is
>the question, the answers are as many as there are programs. But in this thread
>we are talking about a full width alpha-beta tree (at least, since DB had
>singular extensions, which requires extra searches), of some fixed depth search
>in a given program (that is, move ordering and evaluation forms the tree).

I suggest that you lookup with the CCC search engine the dozens of posts that
shot *ME* down when I tried to insist that a ply is a ply is a ply.

The thorough and convincing arguements against it showed that I was clearly
wrong.

As you are clearly, unmistakeably, and totally wrong right now.



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