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Subject: Re: A question for all chess programmers!!!

Author: Dann Corbit

Date: 17:44:38 01/04/99

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On January 04, 1999 at 20:09:15, Eugene Nalimov wrote:

>On January 04, 1999 at 19:52:21, Dann Corbit wrote:
>
>>After having stepped through these end-games, I think that the problem is the
>>horizon effect. The draws are so far away, that they cannot be seen.  Which
>>brings up an interesting question:
>>Do endgame tablebase files contain draw data *as well as* checkmate data, so
>>that when you are behind a draw could be discovered?  This seems (to my feeble
>>way of thinking) to be just as valuable as checkmate data.  If not, it seems
>>worthwhile to construct draw endgame tablebase files just as construction of
>>checkmate database files is valuable.
>
>Based on my understanding, any program that has access to
>the corresponding TB must declare those positions as draws
>(I myself have no chess program here, so I cannot check my
>statement).
After turning logging on, I see that Crafty did see that the position was drawn,
but is "trying for swindle":

White(1): setboard 8/6kP/5N2/5K2/8/8/8/8 w - -
White(1): go
end-game phase
              clearing hash tables
Drawn at root, trying for swindle.
              time surplus   0.00  time limit 12:50 (12:50)
              depth   time  score   variation (1)
                6->   0.07   6.91   1. Ke6 Kh8 2. Kd6 Kg7 3. Ke5 Kh8
                7     0.07   6.91   1. Ke6 Kh8 2. Kd6 Kg7 3. Ke5 Kh8 4.
                                    Ke6
                7->   0.14   6.91   1. Ke6 Kh8 2. Kd6 Kg7 3. Ke5 Kh8 4.
                                    Ke6
                8     0.16   6.99   1. Ke6 Kh8 2. Kd6 Kg7 3. Ke5 Kh8 4.
etc.
also:
White(1): setboard 5k2/6r1/4Q3/8/8/8/8/7K b - -
              puzzling over a move to ponder.
end-game phase
              clearing hash tables
              depth   time  score   variation (1)
Black(1): Rh7+ [pondering]
              clearing hash tables
Drawn at root, trying for swindle.
              time surplus   0.00  time limit 12:50 (12:50)
              depth   time  score   variation (1)
                6->   0.06   4.60   2. Kg2 Re7 3. Qf6+ Ke8 4. Kg3 Kd7 5.
                                    Kf4
                7     0.13   4.60   2. Kg2 Re7 3. Qf6+ Ke8 4. Kg3 Kd7 5.
                                    Kf4 Re6
                7->   0.14   4.60   2. Kg2 Re7 3. Qf6+ Ke8 4. Kg3 Kd7 5.
                                    Kf4 Re6
                8     0.31   4.60   2. Kg2 Re7 3. Qf6+ Ke8 4. Kg3 Kd7 5.
                                    Kf4 Re6 6. Qh8
                8->   0.41   4.60   2. Kg2 Re7 3. Qf6+ Ke8 4. Kg3 Kd7 5.
                                    Kf4 Re6 6. Qh8
                9     1.13   4.65   2. Kg2 Re7 3. Qf6+ Ke8 4. Kg3 Kd7 5.
                                    Kf4 Re6 6. Qf7+ Kd6 7. Qg8
                9->   1.22   4.65   2. Kg2 Re7 3. Qf6+ Ke8 4. Kg3 Kd7 5.
                                    Kf4 Re6 6. Qf7+ Kd6 7. Qg8



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