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Subject: Can anyone calculate this to mate?

Author: Jeremiah Penery

Date: 23:29:31 03/30/00


This position came from Valentin Albillo's site, on one of the endgame pages.

In this position:

[D]8/8/8/8/3p4/2k1p3/2N1P3/3K4 w - -

White is supposed to capture the first black pawn on ply 39 (move 20), and the
second one shortly after.  I ran my modified Crafty on this with all 5-man TBs
to a depth of 45, with some strange results:

White(1): 8/8/8/8/3p4/2k1p3/2N1P3/3K4/ w
analyze.White(1): end-game phase
              clearing hash tables
              time surplus   0.00  time limit 30.00 (3:00)
         nss  depth   time  score   variation (1)
<It's not very interesting until about here.>
               37->  58:30   0.78   1. Ne1 Kb3 2. Nd3 Kc3 3. Ne5 Kb3 4.
                                    Nd3
               38    58:37     --   1. Ne1
               38    58:41     ++   1. Ne1!!
               38    62:52   4.54   1. Ne1 Kb2 2. Nd3+ Kc3 3. Nc1 Kb2 4.
                                    Na2 Kb1 5. Nb4 Kb2 6. Nd5 Kb3 7. Nc7
                                    Kc3 8. Nb5+ Kc4 9. Nd6+ Kb3 10. Ne4
                                    Kb2 11. Nc5 Kc3 12. Ke1 Kb2 13. Ne6
                                    Kc3 14. Nf4 Kc4 15. Kf1 Kc5 16. Kg2
                                    Kd6 17. Nd3 Ke7 18. Kf3 Kf8 19. Ke4
                                    Kg7 20. Kxd4 Kf6 21. Kxe3

<This is what the analysis shows should happen, approximately.  Looks good so
far.  We're into TBs now, but since it's too close to the leaf, Crafty doesn't
probe them here, I think.>

               38->  62:52   4.54   1. Ne1 Kb2 2. Nd3+ Kc3 3. Nc1 Kb2 4.
                                    Na2 Kb1 5. Nb4 Kb2 6. Nd5 Kb3 7. Nc7
                                    Kc3 8. Nb5+ Kc4 9. Nd6+ Kb3 10. Ne4
                                    Kb2 11. Nc5 Kc3 12. Ke1 Kb2 13. Ne6
                                    Kc3 14. Nf4 Kc4 15. Kf1 Kc5 16. Kg2
                                    Kd6 17. Nd3 Ke7 18. Kf3 Kf8 19. Ke4
                                    Kg7 20. Kxd4 Kf6 21. Kxe3
               39    63:01     ++   1. Ne1!!
               39-> 124:20   4.93   1. Ne1 Kb2 2. Nd3+ Kc3 3. Nc1 Kb2 4.
                                    Na2 Kb1 5. Nb4 Kb2 6. Nd5 Kb3 7. Nc7
                                    Kc3 8. Nb5+ Kc4 9. Nd6+ Kb3 10. Ne4
                                    Kb2 11. Nc5 Kc3 12. Ke1 Kb2 13. Ne6
                                    Kc3 14. Nf4 Kc4 15. Kf1 Kc5 16. Kg2
                                    Kd6 17. Nd3 Ke7 18. Kf3 Kf8 19. Ke4
                                    Kg7 20. Kxd4 Kf6 21. Kxe3
               40   125:13     ++   1. Ne1!!
               40-> 417:29   5.32   1. Ne1 Kb2 2. Nd3+ Kc3 3. Nc1 Kb2 4.
                                    Na2 Kb1 5. Nb4 Kb2 6. Nd5 Kb3 7. Nc7
                                    Kc3 8. Nb5+ Kc4 9. Nd6+ Kb3 10. Ne4
                                    Kb2 11. Nc5 Kc3 12. Ke1 Kb2 13. Ne6
                                    Kc3 14. Nf4 Kc4 15. Kf1 Kc5 16. Kg2
                                    Kd6 17. Nd3 Ke7 18. Kf3 Kf8 19. Ke4
                                    Kg7 20. Kxd4 Kf6 21. Kxe3

<Still, looking good, as before.>

               41   418:44     --   1. Ne1
               41   421:21   0.00   1. Ne1 Kb2 2. Nd3+ Kc3 3. Nc5 Kc4 4.
                                    Ne4 d3 5. exd3+ <HT>

<What happened?  The drawscore remains until...>

               43-> 530:24   0.00   1. Ne1 Kb2 2. Nd3+ Kc3 3. Nc5 Kc4 4.
                                    Ne4 d3 5. exd3+ <HT>
               44   548:34     ++   1. Ne1!!
               44-> 1233:04   0.39   1. Ne1 Kb2 2. Nd3+ Kc3 3. Nc5 Kc4 4.
                                    Ne4 d3 5. exd3+ <HT>
               45   1234:35     ++   1. Ne1!!

<Will the score go back up again?  Will it find mate from the TBs?>

I'm wondering if someone with a faster machine, with more memory (for TB cache,
primarily - my HD was going nuts, practically grinding my whole machine to a
halt) could run this until it sees mate.  I'd like to know how far out it is. :)

Thanks,
Jeremiah



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