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Subject: Re: Why this move is so difficult for engines ?

Author: Robert Hyatt

Date: 21:29:55 10/17/02

Go up one level in this thread


On October 17, 2002 at 04:51:28, Christophe Drieu wrote:

>[D] 8/4k3/4p3/pp5p/6p1/2P2rP1/PPK2R1P/8 w - - 0 1
>
>Rxf3 !


I tried this with the current crafty, which has some endgame changes in it.
Here is what it
says on my 750mhz laptop:

              clearing hash tables
              time surplus   0.00  time limit 166:39 (166:39)
              depth   time  score   variation (1)
                1     0.00   1.11   1. Rxf3 gxf3
                1->   0.00   1.11   1. Rxf3 gxf3
                2     0.00   1.11   1. Rxf3 gxf3
                2->   0.00   1.11   1. Rxf3 gxf3
                3     0.00   1.31   1. Rxf3 gxf3 2. Kd3
                3->   0.00   1.31   1. Rxf3 gxf3 2. Kd3
                4     0.00     --   1. Rxf3
                4     0.00  -0.42   1. Rxf3 gxf3 2. Kd3 b4 3. cxb4
                4->   0.01  -0.42   1. Rxf3 gxf3 2. Kd3 b4 3. cxb4
                5     0.01     ++   1. Rxf3!!
                5     0.01   0.85   1. Rxf3 gxf3 2. Kd3 f2 3. Ke2 h4 4.
                                    Kxf2
                5->   0.01   0.85   1. Rxf3 gxf3 2. Kd3 f2 3. Ke2 h4 4.
                                    Kxf2
                6     0.02   0.76   1. Rxf3 gxf3 2. Kd3 h4 3. Ke3 e5 4.
                                    Kxf3
                6->   0.02   0.76   1. Rxf3 gxf3 2. Kd3 h4 3. Ke3 e5 4.
                                    Kxf3
                7     0.04   0.86   1. Rxf3 gxf3 2. Kd3 e5 3. Ke3 e4 4.
                                    a3
                7->   0.04   0.86   1. Rxf3 gxf3 2. Kd3 e5 3. Ke3 e4 4.
                                    a3
                8     0.07     --   1. Rxf3
                8     0.12  -0.19   1. Rxf3 gxf3 2. Kd3 e5 3. a4 h4 4.
                                    Ke3 e4 5. gxh4
                8->   0.16  -0.19   1. Rxf3 gxf3 2. Kd3 e5 3. a4 h4 4.
                                    Ke3 e4 5. gxh4
                9     0.19     ++   1. Rxf3!!
                9     0.26   0.77   1. Rxf3 gxf3 2. Kd3 e5 3. Ke3 e4 4.
                                    Kf2 Kd6 5. Ke3
                9->   0.29   0.77   1. Rxf3 gxf3 2. Kd3 e5 3. Ke3 e4 4.
                                    Kf2 Kd6 5. Ke3
               10     0.47   0.66   1. Rxf3 gxf3 2. Kd3 e5 3. b3 Kd6 4.
                                    Ke3 Kd5 5. Kxf3 b4 6. cxb4 axb4
               10->   0.66   0.66   1. Rxf3 gxf3 2. Kd3 e5 3. b3 Kd6 4.
                                    Ke3 Kd5 5. Kxf3 b4 6. cxb4 axb4
               11     0.97   0.63   1. Rxf3 gxf3 2. Kd3 e5 3. b3 e4+ 4.
                                    Ke3 Kd6 5. a4 bxa4 6. bxa4 Kd5 7. Kf2
               11->   1.33   0.63   1. Rxf3 gxf3 2. Kd3 e5 3. b3 e4+ 4.
                                    Ke3 Kd6 5. a4 bxa4 6. bxa4 Kd5 7. Kf2
               12     2.00   0.51   1. Rxf3 gxf3 2. Kd3 e5 3. b3 e4+ 4.
                                    Ke3 Kd6 5. a4 bxa4 6. bxa4 Kd5 7. Kf2
                                    Kc4
               12->   3.04   0.51   1. Rxf3 gxf3 2. Kd3 e5 3. b3 e4+ 4.
                                    Ke3 Kd6 5. a4 bxa4 6. bxa4 Kd5 7. Kf2
                                    Kc4
               13     4.80   0.60   1. Rxf3 gxf3 2. Kd3 e5 3. a4 bxa4 4.
                                    h3 e4+ 5. Ke3 Kf6 6. c4 Ke5 7. c5 Kd5
               13->   6.61   0.60   1. Rxf3 gxf3 2. Kd3 e5 3. a4 bxa4 4.
                                    h3 e4+ 5. Ke3 Kf6 6. c4 Ke5 7. c5 Kd5
               14     9.40   0.69   1. Rxf3 gxf3 2. Kd3 e5 3. a4 bxa4 4.
                                    Ke3 e4 5. h4 Kd6 6. g4 a3 7. bxa3 f2
                                    8. Kxf2
               14->  15.35   0.69   1. Rxf3 gxf3 2. Kd3 e5 3. a4 bxa4 4.
                                    Ke3 e4 5. h4 Kd6 6. g4 a3 7. bxa3 f2
                                    8. Kxf2
               15    18.51     ++   1. Rxf3!!
               15    25.86   2.30   1. Rxf3 gxf3 2. Kd3 e5 3. a4 bxa4 4.
                                    Ke3 e4 5. h4 f2 6. Kxf2 Kd6 7. g4 e3+
                                    8. Kxe3 a3 9. bxa3
               15->  39.28   2.30   1. Rxf3 gxf3 2. Kd3 e5 3. a4 bxa4 4.
                                    Ke3 e4 5. h4 f2 6. Kxf2 Kd6 7. g4 e3+
                                    8. Kxe3 a3 9. bxa3
               16    59.36     ++   1. Rxf3!!
               16->   2:05   2.69   1. Rxf3 gxf3 2. Kd3 e5 3. a4 bxa4 4.
                                    Ke3 e4 5. h4 f2 6. Kxf2 Kd6 7. g4 e3+
                                    8. Kxe3 a3 9. bxa3
(note last PV is not real.  it is PV from previous ply)
               17     3:16   2.83   1. Rxf3 gxf3 2. Kd3 Kd6 3. Ke3 Kd5
                                    4. Kxf3 a4 5. b3 axb3 6. axb3 e5 7.
                                    h3 Kd6 8. Ke4 Ke6 9. Kd3 h4 10. gxh4
\


If I follow the basic idea of Rf3 gxf3 Kd3 e5, then crafty seems to prefer Ke3
at shallow
depths, h3 as it goes deeper...



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