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Subject: Re: Mate in 14

Author: Günther Simon

Date: 14:27:47 12/02/05

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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



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