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Subject: Re: Keeping the last pawn

Author: Robert Hyatt

Date: 16:21:06 11/27/00

Go up one level in this thread


On November 26, 2000 at 22:00:48, Mike S. wrote:

>On November 26, 2000 at 21:30:07, Robert Hyatt wrote:
>
>>Actually the rule generally says "if ahead in material, trade pieces but
>>_not_ pawns...  if behind in material, trade pawns but not pieces..."
>>
>>That solves your problem...
>
>Thanks! What does Crafty do in this position (I don't have a 17.x version
>installed yet at the moment)?
>
>Regards

Here is the current version's output:


         nss  depth   time  score   variation (1)
                1     0.00   0.00   1. hxg5 Nxg5+
                1     0.00     ++   1. h5!!
                1     0.00   1.09   1. h5
                1     0.00   1.36   1. Ra7+ Kf6
                1->   0.00   1.36   1. Ra7+ Kf6
                2     0.00   1.19   1. Ra7+ Ke6 2. h5
                2->   0.01   1.19   1. Ra7+ Ke6 2. h5
                3     0.01     --   1. Ra7+
                3     0.01   0.42   1. Ra7+ Kf6 2. Rxf7+ Kxf7 3. hxg5
                3     0.03   0.74   1. h5 h6 2. Rc6
                3->   0.03   0.74   1. h5 h6 2. Rc6
                4     0.04   0.72   1. h5 h6 2. Rc6 Nd6+ 3. Kf3
                4->   0.05   0.72   1. h5 h6 2. Rc6 Nd6+ 3. Kf3
                5     0.06   0.79   1. h5 h6 2. Rc6 Nd6+ 3. Ke5 Nf7+ 4.
                                    Kf5
                5->   0.36   0.79   1. h5 h6 2. Rc6 Nd6+ 3. Ke5 Nf7+ 4.
                                    Kf5
                6     0.37   0.74   1. h5 h6 2. Rc6 Kd7 3. Rf6 Ke7
                6->   0.56   0.74   1. h5 h6 2. Rc6 Kd7 3. Rf6 Ke7
                7     0.62   1.02   1. h5 h6 2. Kf5 Kf8 3. Re6 Kg7 4. Kg4
                7->   1.31   1.02   1. h5 h6 2. Kf5 Kf8 3. Re6 Kg7 4. Kg4
                8     1.37   1.21   1. h5 h6 2. Kf5 Kf8 3. Ra7 Nd8 4. Kg4
                                    Ne6
                8->   1.57   1.21   1. h5 h6 2. Kf5 Kf8 3. Ra7 Nd8 4. Kg4
                                    Ne6
                9     1.70   1.42   1. h5 h6 2. Kf5 Kf8 3. Ra7 Nh8 4. Kg4
                                    Nf7 5. Rd7
         (3)    9->   2.14   1.42   1. h5 h6 2. Kf5 Kf8 3. Ra7 Nh8 4. Kg4
                                    Nf7 5. Rd7
               10     2.31     ++   1. h5!!
         (2)   10     2.60   2.27   1. h5 h6 2. Kf5 Nd6+ 3. Kg6 Ne4 4.
                                    Kxh6 Kf7 5. Ra4 Nc3 6. Rd4
               10->   3.43   2.27   1. h5 h6 2. Kf5 Nd6+ 3. Kg6 Ne4 4.
                                    Kxh6 Kf7 5. Ra4 Nc3 6. Rd4
               11     4.53   2.32   1. h5 h6 2. Kf5 Nd6+ 3. Kg6 Ne4 4.
                                    Kxh6 Kf7 5. Ra4 Nc5 6. Rg4 Ne6
         (2)   11->   6.20   2.32   1. h5 h6 2. Kf5 Nd6+ 3. Kg6 Ne4 4.
                                    Kxh6 Kf7 5. Ra4 Nc5 6. Rg4 Ne6
               12     8.39   2.35   1. h5 h6 2. Kf5 Nd6+ 3. Kg6 g4 4. Ra4
                                    g3 5. Ra3 g2 6. Re3+ Kd7 7. Rg3 Ke6
                                    8. Rxg2


Note that this code has been significantly rewritten, so older versions probably
will behave a bit differently here.  It was time to clean up the detection of
"one side can't win" and do it right, rather than in a kludge.  It now knows
that KR vs KNP is not a win for the KR, ditto for KRB vs KRP and so forth...
the extra piece isn't enough.








>M.Scheidl
>
>>>[D]8/4kn1p/R7/6p1/4K2P/8/8/8 w - - 0 49
>>>
>>>49.Kf5? gxh4, and the game ended in a draw.
>>>
>>>The only winning move seems to be 49.h5.



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