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Subject: Re: Tablebases Again

Author: Ernst A. Heinz

Date: 02:53:21 10/12/98

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On October 12, 1998 at 05:02:09, Bernhard Bauer wrote:

>On October 11, 1998 at 01:37:52, Bruce Moreland wrote:
>
>>
>>On October 10, 1998 at 21:25:25, James T. Walker wrote:
>>
>>>I tested Crafty15.20 tonight and it solves the problem instantly.  I also tested
>>>the following computers/programs. ALL solved the mate instantly.
>>>Fritz5.0,Rebel Decade 2.0,Rex2.3,Fidelity Mach3,Fidelity Mach IV,M-Chess Pro 3.5
>>>M-Chess Pro 5.0,Genius 4.0, Genius 2.0,Kasparov's Gambit,CM4000,CM5000,CM5500
>>>and my handheld Mephisto Marco Polo(USCF about 1800).  I do not have a single
>>>program/computer that does not solve this instantly.  Maybe the creator of JR.
>>>should take a look at this problem.
>>>Jim Walker
>>
>>After you check to see if they find the mate, please also check to see if you
>>can play out the main line by making each move.  Also, check to see whether it
>>works with colors reversed.  I bet that there are cases where programs will call
>>the game a draw, without executing the mate, or without allowing you to execute
>>the mate.
>>
>>bruce
>
>Yes, we should be carefull in this type of position.
>For the following position:
>White: Kc8, Bg8
>Black: Ka8, Ba7
>White to move
>FEN: k1K3B/b/8/8/8/8/8/8 w
>Crafty 15.20 will move Bh7 instead of mating with Be5# and it will tell us
>game is a draw due to insufficient material. The learning is wrong too.
>Crafty says: learning position, wtm=1  value=-66
>
>By the way, the "insufficient material feature" has further consequences.
>For the following position, which is a mate in 6 Crafty has no clue.
>FEN: 8/1k1K4/8/8/1pN5/1N6/8/8 w

"DarkThought" knows about insufficient material but *also* about the
exceptions. It solves your above examples within fractions of a second.

As I have already pointed out before, the efficient implementation framework
for interior-node recognition allows us to incorporate such knowledge with
hardly any losse of search speed.

=Ernst=



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