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Subject: Re: A test position(perpetual check),chessmaster and Fritz have problems

Author: James T. Walker

Date: 09:59:27 10/21/00

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On October 21, 2000 at 10:56:53, Uri Blass wrote:

>On October 21, 2000 at 09:27:22, James T. Walker wrote:
>
>>On October 21, 2000 at 05:28:14, Uri Blass wrote:
>>
>>>I composed this position to see if chessmaster can see perpetual check.
>>>
>>>[D]4k3/6RQ/6PP/8/r7/8/r7/7K b - - 0 1
>>>
>>>The target is to see 0.00 score
>>>
>>>I found that chessmaster does not see the draw even after some minutes but after
>>>Ra1+ Kg2 it can see the draw very quickly in clearly smaller depth.
>>>
>>>The same after Ra1+ Kh2
>>>
>>>I tried also Fritz5.32 and it does not see the draw at least after a short time.
>>>
>>>If I give Fritz5.32 the moves  Ra1+ Kg2 it can see the draw but after Ra1+ Kh2
>>>it has problems to see the draw.
>>>
>>>Fritz5.32 expects Kg2 when it plays Ra1+ and wants to play Kg2 at depth 13 with
>>>evaluation 0.00.
>>>
>>>How many squares can the white king visit before the repetition?(it is clear
>>>that the white king cannot visit all the 21 squares (b1-b3... h1-h3))
>>>
>>>Uri
>>
>>Hello Uri,
>>Why can't the White King visit all 21 squares?  If the King takes the pattern of
>>h2,g1,g2,f1,f2,e1,e2,d1,d2,c1,c2,b1,b2,b3,b2,c3,c2,d3,d2,e3,e2,f3,f2,g3,g2,h3,h2,h1,g2,f1,f2,e1,e2,d1,d2,c1,c2,b1,
>>it has visited all 21 squares and taken 38 moves without hitting the same square
>>3 times.  What did I miss?
>>Jim
>
>You missed the fact that computers are supposed to evaluated second repetition
>in the search as a draw.
>
>Uri

Hello Uri,
I didn't know that.  What is the reasoning behind that?  There is a lot I don't
know about computer chess! :-)
Jim



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