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Subject: Re: Junior 8 doesn't see this simple mate

Author: Omid David Tabibi

Date: 11:35:25 08/21/03

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On August 21, 2003 at 14:13:00, Sune Fischer wrote:

>On August 21, 2003 at 10:41:26, Omid David Tabibi wrote:
>
>>On August 21, 2003 at 10:29:15, Omid David Tabibi wrote:
>>
>>>On August 21, 2003 at 10:10:54, Mihaly Szalai wrote:
>>>
>>>>[D]8/8/8/4p1p1/6N1/5p1p/5K2/7k w - - 0 1
>>>>
>>>>All the programs I've tried see the mate
>>>>except Junior 7 and 8. They go to depth=63
>>>>and score=0.00 in a few seconds then stop.
>>>>Why? One knight is not enough to mate?
>>>
>>>Interesting case. I guess when one side is left with a knight or a bishop,
>>>Junior sets beta = 0, i.e., that he cannot achieve more than a draw. It is a
>>>kind of tradeoff: in many positions this knowledge saves a lot of search (by
>>>pruning the tree), but in very rare examples like the above, it produces
>>>erroneous results.
>>>
>>>I believe that the risk is negligible in comparison to the considerable gain.
>>>However, as a matter of principle I'm against such "assumptions"...
>>
>>To quote Eric Bogosian in the movie 'Under Siege 2: Dark Territory':
>>
>>"Assumption is the mother of all f**k-ups" :)
>
>Then you can disable nullmove as well, that f**k ups as well some times.

I use verified null-move pruning, it doesn't f**k-up :)


>
>-S.



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