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Subject: Re: Mate in 14

Author: Zheng Zhixian

Date: 23:17:42 12/03/05

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On December 02, 2005 at 17:27:47, Günther Simon wrote:

>On December 02, 2005 at 17:17:50, Robert Hyatt wrote:
>
>>On December 02, 2005 at 15:49:11, Paul Jacobean Sacral wrote:
>>
>>>On December 02, 2005 at 15:19:51, chandler yergin wrote:
>>>
>>>>On December 02, 2005 at 14:56:48, Uri Blass wrote:
>>>
>>>>>Engines can say mate in 14 even when there is mate in 11 but not the opposite.
>>>>>
>>>>>Engines should say mate in 11 for white only when they checked all defences of
>>>>>black and found that there is no defence against mate in 11.
>>>
>>>>Engines evaluate all moves 1/2 move i.e. 1 Ply at a time.
>>>>Nothing more.. nothing less.
>>>>The deeper the search the better the evaluation.
>>>>You assert bugs when there is none.
>>>
>>>Excuse me, but with replies like that people will start to think that you are a
>>>troll. Please don't explain to Uri Blass how engines work: He has written an
>>>engine himself.
>>>
>>>Call it bug, mistake, error or whatever you like: If the shortest possible mate
>>>in a position is #14 and an engine displays #11, there is something wrong. Maybe
>>>a rare effect of nullmove pruning or something like that... but #11 is simply
>>>wrong and not a "better evaluation!" :)
>>>
>>>Yours truly Paul J. Sacral
>>
>>
>>That is completely correct.  If an engine claims a shorter mate, and it is
>>proven the mate is longer than that, then the engine has a bug, pure and simple.
>> The inverse is not true, since many engines will find a deeper mate and quite
>>before finding the absolute shortest mate (some like Crafty won't do this except
>>when EGTBs are involved) and this is not necessarily a bug, but an artifact of
>>how the search is extended.
>>
>>I am not sure why this has become "disinformation central" all of a sudden...
>
>Bob, this is not 'all of a sudden'. It was always there in every post
>from CY since ever and in times he writes 20+ posts a day it simply
>looks like that over here...
>
>Guenther

And that's only the beginning, he then moves the same question to CTF, where
people like Bruce Moreland , Ulrich Tuerke have to say the same thing over
AGAIN.




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