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Subject: Re: Rook & Pawn Ending with Perpetual Check and Stalemate

Author: Uri Blass

Date: 11:55:44 03/31/01

Go up one level in this thread


On March 31, 2001 at 12:53:29, Tony Werten wrote:

>On March 31, 2001 at 09:22:57, Ferdinand S. Mosca wrote:
>
>>Hi everyone,
>>
>>A position from an actual game which caught my interest while
>>playing an engine match at G60.
>>
>>[D]3r4/5k2/5p2/6pp/5p2/1p6/p2R4/K3R3 b - - 0 1
>>Is there any program that can evaluate this simple ending logically.
>>
>>The trap here is the move ...Rxd2, this may not win but it only draws.
>>There is perpetual check and stalemate if black plays ...Rxd2. Many programs
>>probably find the perpetual coming, but at what time do your favorite programs
>>give a 0.0 or near 0.0 score?
>
>Are you sure ? Result of XiniX: (running in kind of debug so it's even slower
>than normal )
>
>18/34 35,825 565s 125 Kn/s 1. .. Rxd2 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+
>Kd6 6.Re6+ Kc7 7.Re7+ Rd7 8.Re1 f3 9.Kb2 f2 10.Rf1 Re7

It is obvious that 7.Rc6+ is better than 7.Re7+

I think that it is better to let xinix to play against itself in order to check
if it is a draw before asking.

Here is some analysis by Deep Fritz
I asked it for the next best move and this is the reason that it got down from
depth 20 to depth 1.

I did not use most of the tablebases but Deep Fritz shows some tablebase hits
inspite of it.

New position
3r4/5k2/5p2/6pp/5p2/1p6/p2R4/K3R3 b - - 0 1

Analysis by Deep Fritz:

1...Rxd2!
  -+  (-6.41)   Depth: 1/2   00:00:00
1...Rxd2!
  -+  (-9.53)   Depth: 1/2   00:00:00
1...Rxd2 2.Rf1
  -+  (-9.59)   Depth: 2/5   00:00:00
1...Rxd2 2.Rh1 h4
  -+  (-9.78)   Depth: 3/6   00:00:00
1...Rxd2!
  -+  (-10.16)   Depth: 4/8   00:00:00
1...Rxd2 2.Rh1 g4 3.Rf1 f3
  -+  (-10.16)   Depth: 5/12   00:00:00  1kN
1...Rxd2!
  -+  (-10.47)   Depth: 6/13   00:00:00  2kN
1...Rxd2! 2.Re7+ Kg6 3.Re1 g4 4.Rh1 Kg5
  -+  (-10.56)   Depth: 6/14   00:00:00  3kN
1...Rxd2--
  -+  (-10.19)   Depth: 7/14   00:00:00  6kN
1...Rxd2-- 2.Re7+ Kf8 3.Re8+ Kg7
  -+  (-9.84)   Depth: 7/19   00:00:00  10kN
1...Rxd2 2.Re7+ Kf8 3.Re8+ Kg7 4.Re7+ Kg8
  -+  (-9.66)   Depth: 8/21   00:00:00  15kN
1...Rxd2--
  -+  (-9.34)   Depth: 9/20   00:00:00  25kN
1...Rxd2-- 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke4 5.Rg1 f3 6.Rh1 f2
  -+  (-9.16)   Depth: 9/22   00:00:00  32kN
1...Rxd2--
  -+  (-8.84)   Depth: 10/22   00:00:00  48kN
1...Rxd2-- 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd7 6.Re7+ Kc6 7.Re6+
  -+  (-8.41)   Depth: 10/25   00:00:00  68kN
1...Rxd2--
  -+  (-8.09)   Depth: 11/25   00:00:00  108kN
1...Rxd2--
  -+  (-8.09)   Depth: 11/27   00:00:00  125kN
1...Rxd2!
  -+  (-8.41)   Depth: 12/29   00:00:00  218kN
1...Rxd2! 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd6 6.Re6+ Kc5 7.Re5+
  -+  (-8.47)   Depth: 12/29   00:00:00  250kN
1...Rxd2--
  -+  (-8.16)   Depth: 13/29   00:00:00  433kN
1...Rxd2-- 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd6 6.Re6+ Kc7 7.Re7+
  -+  (-7.78)   Depth: 13/29   00:00:00  485kN
1...Rxd2 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd6 6.Re6+ Kc7 7.Re7+
  -+  (-7.81)   Depth: 14/30   00:00:01  872kN
1...Rxd2 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd6 6.Re6+ Kc7 7.Rc6+
  -+  (-7.81)   Depth: 15/32   00:00:03  2164kN
1...Rxd2--
  -+  (-7.50)   Depth: 16/33   00:00:05  3852kN
1...Rxd2-- 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd6 6.Re6+ Kc7 7.Rc6+
  -+  (-6.97)   Depth: 16/36   00:00:06  4566kN
1...Rxd2 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd6 6.Re6+ Kc7 7.Rc6+
  -+  (-6.72)   Depth: 17/35   00:00:15  11055kN
1...Rxd2--
  -+  (-6.41)   Depth: 18/41   00:00:42  30320kN, tb=1
1...Rxd2-- 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd6 6.Re6+ Kc7 7.Rc6+
  -+  (-6.13)   Depth: 18/41   00:00:45  32559kN, tb=1
1...Rxd2 2.Re7+ Kg6 3.Rg7+ Kf5 4.Rxg5+ Ke6 5.Re5+ Kd6 6.Re6+ Kc7 7.Rc6+
  -+  (-6.09)   Depth: 19/42   00:02:35  113283kN, tb=2
1...Rxd2--
  -+  (-5.78)   Depth: 20/45   00:06:45  298974kN, tb=7
1...Rxd2--
  -+  (-5.78)   Depth: 20/45   00:06:51  303275kN, tb=7
1...b2+!
  -+  (-1.69)   Depth: 1/3   00:08:09, tb=9
1...b2+! 2.Rxb2
  -+  (-2.47)   Depth: 1/3   00:08:09, tb=9
1...Rb8!
  -+  (-3.03)   Depth: 1/4   00:08:09, tb=9
1...Rb8!
  -+  (-4.44)   Depth: 1/4   00:08:09, tb=9
1...Rb8 2.Rb2
  -+  (-4.16)   Depth: 2/5   00:08:09, tb=9
1...Ra8!
  -+  (-4.19)   Depth: 2/5   00:08:09, tb=9
1...Ra8 2.Rb2 Ra3
  -+  (-4.19)   Depth: 3/10   00:08:09, tb=9
1...Rb8!
  -+  (-4.22)   Depth: 3/10   00:08:09, tb=9
1...Rb8! 2.Rd7+
  -+  (-4.25)   Depth: 3/10   00:08:09, tb=9
1...Rb8 2.Rh2 h4 3.Kb2
  -+  (-4.38)   Depth: 4/8   00:08:09  1kN, tb=9
1...Rb8 2.Kb2 f3 3.Rd7+ Kg6 4.Rde7
  -+  (-4.34)   Depth: 5/12   00:08:09  2kN, tb=9
1...Rb8--
  -+  (-4.03)   Depth: 6/14   00:08:09  8kN, tb=9
1...Rb8--
  -+  (-4.03)   Depth: 6/14   00:08:09  8kN, tb=9
1...Rb8 2.Rd7+ Kg6 3.Rd3 h4 4.Kb2 g4 5.Rxb3
  -+  (-3.91)   Depth: 7/16   00:08:09  19kN, tb=9
1...Rb8 2.Kb2 h4 3.Rd3 g4 4.Rxb3 Ra8 5.Ra1
  -+  (-3.66)   Depth: 8/19   00:08:09  55kN, tb=9
1...Rb8 2.Kb2 g4 3.Rd7+ Kg6 4.Rd3 h4 5.Rxb3 Ra8 6.Ra1
  -+  (-3.81)   Depth: 9/18   00:08:09  156kN, tb=9
1...Rb8 2.Rh1 h4 3.Kb2 f5 4.Rd3 Ra8 5.Rxb3 g4 6.Ra1
  -+  (-3.81)   Depth: 10/22   00:08:10  449kN, tb=9
1...Rb8 2.Rf1 Rb4 3.Kb2 g4 4.Kc3 Rb7 5.Rb2 h4
  -+  (-3.84)   Depth: 11/24   00:08:12  1711kN, tb=9
1...Rb8--
  -+  (-3.53)   Depth: 12/25   00:08:13  2648kN, tb=9
1...Rb8--
  -+  (-3.53)   Depth: 12/26   00:08:14  2802kN, tb=9
1...Rb8 2.Rf1 h4 3.Rf3 g4 4.Rxf4 f5 5.Rxf5+ Ke6 6.Rf4
  -+  (-3.25)   Depth: 13/28   00:08:20  6931kN, tb=9
1...Rb8 2.Rf1 Rb4 3.Kb2 g4 4.Rd7+ Kg6 5.Rd3 f3
  -+  (-3.44)   Depth: 14/28   00:08:40  20173kN, tb=9
1...Rb8--
  -+  (-3.13)   Depth: 15/32   00:08:56  31059kN, tb=9
1...Rb8--
  -+  (-3.13)   Depth: 15/32   00:09:01  34484kN, tb=9
1...Rb8!
  -+  (-3.44)   Depth: 16/32   00:10:07  79244kN, tb=9
1...Rb8! 2.Rf1 Rb4 3.Kb2 g4 4.Rd5 Kg6 5.Rh1 f3 6.Rdxh5 f5
  -+  (-3.69)   Depth: 16/33   00:11:33  137438kN, tb=9
1...Rb8--
  -+  (-3.38)   Depth: 17/34   00:15:51  304328kN, tb=10
1...Rb8--
  -+  (-3.38)   Depth: 17/34   00:16:00  310502kN, tb=10

(blass, tel-aviv 31.03.2001)




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