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Subject: Re: Open Letter by Hsu: Kasparov does not want a rematch

Author: Robert Hyatt

Date: 18:31:24 01/10/00

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On January 10, 2000 at 17:45:21, Jeremiah Penery wrote:

>On January 10, 2000 at 16:30:58, Robert Hyatt wrote:
>
>>No program _ever_ found the draw.  It is over 60 plies deep from the ending
>>position...  which is hopeless unless you start to give a program 24 hours or
>>more to search.
>
>Just since this has come up...
>I let my modified Crafty run on this for about a month over Xmas break...This is
>what it came up with:
>
>I gave it the position before the final move of the game, and told it to search
>that move.
>
>White(45): search Ra6
>              time surplus   0.00  time limit 30.00 (3:00)
>         nss  depth   time  score   variation (1)
>                1->   0.01  -0.58   45. Ra6 Qxc6 46. dxc6
>                2->   0.04  -0.58   45. Ra6 Qxc6 46. dxc6
>                3->   0.06  -0.87   45. Ra6 Qxc6 46. dxc6 Bc7
>                4     0.07     ++   45. Ra6!!
>                4->   0.09   0.33   45. Ra6 Qxc6 46. dxc6 Bc7 47. Ke2
>                5     0.10     --   45. Ra6
>                5->   0.14  -0.07   45. Ra6 Qxc6 46. dxc6 Bc7 47. Ke2 Ke7
>                6     0.17     ++   45. Ra6!!
>                6->   0.19   0.32   45. Ra6 Qxc6 46. dxc6 Bc7 47. Ke2 Ke7
>                7     0.28     ++   45. Ra6!!
>                7->   0.41   0.89   45. Ra6 Qxc6 46. dxc6 h5 47. Ra7+ Be7
>                                    48. Ke2 Rd8 49. Ke3
>                8     0.61     ++   45. Ra6!!
>                8->   0.90   1.28   45. Ra6 Qxc6 46. dxc6 h5 47. Ra7+ Be7
>                                    48. Ke2 Rd8 49. Ke3
>                9->   1.40   1.22   45. Ra6 Qxc6 46. dxc6 Ke8 47. Ra7 Rd8
>                                    48. Rb7 Ra8 49. Rxb5 Bc7
>               10     3.44     ++   45. Ra6!!
>               10->   3.76   1.62   45. Ra6 Qxc6 46. dxc6 Ke8 47. Ra7 Rc8
>                                    48. Ke2 Rc7 49. Ra5 Ke7 50. Rxb5
>               11->   5.78   1.61   45. Ra6 Qxc6 46. dxc6 Kf8 47. Ra7 Rc8
>                                    48. Ke2 h5 49. Rb7 Rc7 50. Rxb5 Ke7
>               12->  20.51   1.72   45. Ra6 Qxc6 46. dxc6 Kf8 47. Ra7 Rc8
>                                    48. Ke2 Bc7 49. Rb7 Ke7 50. Rxb5 Kd6
>                                    51. Ke3
>               13->   2:10   1.68   45. Ra6 Qe3 46. Qd7+ Kg8 47. Qxd6 Rf8
>                                    48. Qe6+ Kh8 49. Qe7 Rg8 50. Bf3 Qc1+
>                                    51. Kf2 Qd2+ 52. Be2 Qf4+ 53. Ke1 Qc1+
>                                    54. Kf2 Qxc3
>               14     3:26     --   45. Ra6
>               14->   7:46   0.51   45. Ra6 Qe3 46. Qxd6 Re8 47. h4 h5
>                                    48. Bf3 Qc1+ 49. Kf2 Qd2+ 50. Be2 Qf4+
>                                    51. Kg1 Qe3+ 52. Kh2 Qf4+ 53. Kh3 Qxf5+
>                                    54. Kh2 Qh7
>               15->  12:51   0.44   45. Ra6 Qe3 46. Qxd6 Re8 47. h4 h5
>                                    48. Bf3 Qc1+ 49. Kf2 Qd2+ 50. Be2 Qf4+
>                                    51. Kg1 Qe3+ 52. Kh2 Qf4+ 53. g3 Qf2+
>                                    54. Kh3 Qxe2 55. Qd7+ Kf8 56. Qxb5
>               16->  24:33   0.65   45. Ra6 Qe3 46. Qxd6 Re8 47. h4 h5
>                                    48. Bf3 Qc1+ 49. Kf2 Qd2+ 50. Be2 Qf4+
>                                    51. Kg1 Qe3+ 52. Kh2 Qf4+ 53. Kh3 Qxf5+
>                                    54. Kh2 Qf4+ 55. Kg1 Qc1+ 56. Kf2 Qh6
>               17->  62:44   0.65   45. Ra6 Qe3 46. Qxd6 Re8 47. h4 h5
>                                    48. Bf3 Qc1+ 49. Kf2 Qd2+ 50. Be2 Qf4+
>                                    51. Kg1 Qe3+ 52. Kh2 Qf4+ 53. Kh3 Qxf5+
>                                    54. Kh2 Qf4+ 55. Kg1 Qe3+ 56. Kf1 Qf4+
>                                    57. Ke1 <HT>
>               18-> 257:24   0.73   45. Ra6 Qe3 46. Qxd6 Re8 47. h4 h5
>                                    48. Bf3 Qc1+ 49. Kf2 Qd2+ 50. Be2 Qf4+
>                                    51. Kg1 Qe3+ 52. Kh2 Qf4+ 53. Kh3 Qxf5+
>                                    54. Kh2 Qf4+ 55. Kg1 Qe3+ 56. Kf1 Qc1+
>                                    57. Kf2 Qf4+ 58. Bf3 Qh6
>               19-> 784:39   0.75   45. Ra6 Qe3 46. Qxd6 Re8 47. h4 h5
>                                    48. Bf3 Qc1+ 49. Kf2 Qd2+ 50. Be2 Qf4+
>                                    51. Kg1 Qe3+ 52. Kh2 Qf4+ 53. Kh3 Qxf5+
>                                    54. Kh2 Qf4+ 55. Kg1 Qe3+ 56. Kf1 Qc1+
>                                    57. Kf2 Qf4+ 58. Bf3 Qd2+ 59. Kf1 Qh6
>               20   5177:33     --   45. Ra6
>
>I was optimistic here...Up until now, it had been following the PV given on the
>Rebel site as the longest drawing PV (36 ply - given below), and I hoped that it
>might have discovered the quiet move (60. ...Qc1) in that line which would allow
>the draw...It was not so, and it changed the entire PV.  I did not know this
>until 3 weeks later, however, because I left for break before the resolution of
>the fail-low.
>
>--
>This is from Ed's page:
>45.Ra6? Qe3! 46.Qxd6 Re8! 47.h4! h5! 48.Bf3 Qc1+ 49.Kf2 Qd2+ 50.Be2 Qf4+ 51.Kg1
>Qe3+ 52.Kh2 Qf4+ 53.Kh3 Qxf5+ 54.Kh2 Qf4+ 55.Kg1 Qe3+ 56.Kf1 Qc1+ 57.Kf2 Qf4+
>58.Ke1 Qc1+ 59.Bd1 Qxc3+ 60.Kf1 Qc1! 61.Ke2 Qb2+ 62.Kf1 Qc1
>--
>               20-> 8855:29   0.00   45. Ra6 Qe3 46. Qxd6 Re8 47. Qe6+ Rxe6
>                                    48. fxe6+ Ke7 49. Bg6 Qc1+ 50. Kf2
>                                    Qb2+ 51. Kg3 Qxc3+ 52. Kh2 Qe3 53.
>                                    Bf5 Qf4+ 54. Kh1 Qxf5 55. Ra7+ Kd8
>                                    56. Ra8+ Kc7 57. e7 Qf1+ 58. Kh2 Qf4+
>                                    59. Kh1 Qc1+ 60. Kh2 Qf4+
>               21-> 20053:38   0.15   45. Ra6 Qe3 46. Qxd6 Re8 47. Qd7+ Re7
>                                    48. Qc6 Qxe4 49. d6 Qd3+ 50. Kg1 Re8
>                                    51. Ra7+ Kf8 52. Qc5 Rd8 53. Rxg7 Qd1+
>                                    54. Kh2 Qxd6 55. Rh7 Qxc5 56. bxc5
>                                    Rd3 57. Rxh6 Ke7
>
>I'm only left wondering why it left the PV it had before...
>
>               22   23388:31     ++   45. Ra6!!
>
>Now I was disappointed that the score is going back up.
>
>It ended up searching about 40000 minutes before I stopped it - the fail-high
>had not resolved.  Total nodes ~= 315 billion.


This may have been a bug.  I had a minor problem with the dynamic drawscore
stuff.  ie normally draw=0, but can drop to -20, etc.  And on a rare occasion
here and there, it could be +20 due to a bug.  I have recently discovered/fixed
this.

I let Crafty run on some powerful hardware after that match, and by playing the
first couple of moves (Qe3 to start) it found a draw score after about a day and
a half or so...

But nobody found it in reasonable time...



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