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Up Topic Rybka Support & Discussion / Rybka Discussion / Simple Endgame knowledge!
- - By richbell (**) Date 2007-12-25 21:35 Edited 2007-12-25 21:45
8/8/4k2r/8/8/8/2K5/1R6 w - - 0 1


We can easily see white to move and wins in couple of seconds after looking at this position. Most of the engines i had tested doesn't show a win that fast. How long does Rybka take to find the mate?

I am not a chess expert, could someone explain why engines find this position so difficult? It should be mate in what? 20-25 moves at the max right (if not less).
Parent - By Vempele (Silver) Date 2007-12-25 23:03
Any engine should find it instantly. In 1 ply if they have a check extension (most do), ditto if they consider check evasions in quiescence. Two plies if they have qsearch at all, and three if they don't.
Parent - By dareapa (**) Date 2007-12-25 23:53
Naum 2.0 find mate 11 8 secs
Parent - By Sesse (****) Date 2007-12-26 00:08
This sure sounds strange. Do you count a "win" as a large positive score (say, +4), or are you specifically demanding the mate? I can understand the mate would take slightly longer, but any engine worth its salt should see that this position is much better for white nearly instantly.

/* Steinar */
Parent - - By Gaмßito (****) Date 2007-12-26 04:44 Edited 2007-12-26 04:49
Tablebases said it's a mate in 16 moves. Of course beginning with the first move that it is: 1. Rb6+.

Fritz 11 has big problems finding the mate without tablebases and also in the correct number of moves. In fact, it also cannot see the mate quickly, at least on my machine.  
 
Although, I do not understand why when Fritz 11 reach to a considerable depth, it began to analyzes very dumb moves where the first move it is not Rb6+ or when after Rb6+ and Ke5 or Kd5 or whatever, white does not reply with the winning move Rxh6. It analyzes too many wrong millions moves where white cannot win at all. A total waste of time. Only after 41 minutes, it finds a mate in 44 moves. Note also that Fritz 11 does not have things very clear.

Here is:

8/8/4k2r/8/8/8/2K5/1R6 w - - 0 1


Analysis by Fritz 11:

1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rc6 Kf5 4.Kd3 Ke5 5.Rc5+ Kf4 6.Kd4
  +-  (6.01)   Depth: 9/15   00:00:00  24kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rc6 Kf5 4.Kd3 Ke5 5.Rc5+ Kd6 6.Kd4 Ke6 7.Re5+
  +-  (6.04)   Depth: 10/15   00:00:00  40kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kd6 6.Ke4 Ke6 7.Rb6+
  +-  (6.31)   Depth: 11/17   00:00:00  78kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rh6 Kd5 6.Rh5+ Ke6 7.Kd4 Kd6 8.Rh6+ Kd7 9.Rb6 Ke7 10.Kd3
  +-  (6.31)   Depth: 12/20   00:00:00  147kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kf4 6.Rc5 Kg3 7.Rc4 Kf3 8.Kd4 Kf4
  +-  (6.32)   Depth: 13/19   00:00:00  255kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Ke6 6.Kd4 Kf6 7.Ke4 Ke6 8.Rb6+ Ke7 9.Ke5 Kd7 10.Rf6
  +-  (6.35)   Depth: 14/20   00:00:00  449kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rh8 Kf5 4.Kd3 Kf4 5.Rh5 Kg4 6.Rb5 Kf4 7.Rc5 Kf3 8.Rc4 Kg2 9.Ke4 Kg3 10.Rb4
  +-  (6.42)   Depth: 15/23   00:00:00  826kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Ra6 Kf5 4.Kd3 Ke5 5.Ra5+ Kd6 6.Kd4 Ke6 7.Rh5 Ke7 8.Rh6 Kd7 9.Ke4 Ke7 10.Rb6 Kd7 11.Ke5
  +-  (6.63)   Depth: 16/23   00:00:00  1252kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rh8 Kf5 4.Kd3 Kf4 5.Rh5 Kg4 6.Rb5 Kf4 7.Rc5 Kf3 8.Rc4 Kg2 9.Ke4 Kg3 10.Rb4 Kg4 11.Rb5 Kg3 12.Rc5 Kg4 13.Rb5
  +-  (6.63)   Depth: 17/26   00:00:01  2153kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rh8 Kf5 4.Kd3 Kf4 5.Rh5 Kg4 6.Rb5 Kf4 7.Rc5 Kf3 8.Rc4 Kg2 9.Ke4 Kg3 10.Rc6
  +-  (6.63)   Depth: 18/25   00:00:01  2905kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rh8 Kf5 4.Kd3 Kf4 5.Rh5 Kg4 6.Rb5 Kf3 7.Rb4 Kg3 8.Ke4 Kg4 9.Rb5 Kh4 10.Ke5 Kg3 11.Rb3+ Kg2 12.Ke4 Kf2 13.Re3
  +-  (6.71)   Depth: 19/26   00:00:02  4235kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rh8 Kf5 4.Kd3 Ke5 5.Rh5+ Kd6 6.Ke4 Kc6 7.Kd4 Kd6 8.Rh6+ Ke7 9.Rb6 Kd7 10.Ke4 Kc7 11.Rh6 Kd7 12.Ke5 Kc7 13.Kd5 Kd7 14.Rh7+ Ke8 15.Ke5 Kd8
  +-  (6.75)   Depth: 20/32   00:00:04  7258kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kd6 6.Ke4 Kc6 7.Rd5 Kc7 8.Ke5 Kc6 9.Ke6 Kb7 10.Rd6 Kc7 11.Kd5 Kc8 12.Kc4 Kc7 13.Kd5
  +-  (6.81)   Depth: 21/29   00:00:06  11517kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kd6 6.Ke4 Kc6 7.Rd5 Kc7 8.Ke5 Kc6 9.Ke6 Kb7 10.Rd6 Kc7 11.Kd5 Kc8 12.Ke5 Kb7 13.Ke4 Kc7 14.Kd5
  +-  (6.96)   Depth: 22/29   00:00:08  13756kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kd6 6.Ke4 Kc6 7.Rd5 Kc7 8.Ke5 Kc6 9.Ke6 Kb7 10.Rd6 Kc7 11.Kd5 Kc8 12.Rh6 Kd7 13.Rh7+ Ke8 14.Rb7 Kd8 15.Ke6 Kc8
  +-  (6.96)   Depth: 23/32   00:00:09  16488kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kd6 6.Ke4 Kc6 7.Rd5 Kb6 8.Ke5 Kc7 9.Rd6 Kc8 10.Ke4 Kb7 11.Kd5 Kb8 12.Rd7 Kc8 13.Ke6 Kb8 14.Rh7 Kc8 15.Kd6 Kb8
  +-  (7.18)   Depth: 24/32   00:00:13  22496kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kd6 6.Kd4 Ke6 7.Rb6+ Kf5 8.Rd6 Kf4 9.Rf6+ Kg4 10.Ke5 Kg3 11.Ke4 Kh4 12.Kf4 Kh3 13.Rd6 Kg2 14.Rd2+ Kf1 15.Rc2 Ke1
  +-  (7.33)   Depth: 25/35   00:00:47  94220kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kd6 6.Kd4 Ke6 7.Rb6+ Kf5 8.Rd6 Kf4 9.Rf6+ Kg4 10.Ke5 Kg3 11.Ke4 Kh4 12.Kf4 Kh3 13.Rd6 Kg2 14.Rd2+ Kf1 15.Rc2 Ke1
  +-  (7.33)   Depth: 26/35   00:00:49  98736kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rb6 Kf5 4.Kd3 Ke5 5.Rb5+ Kd6 6.Kd4 Ke6 7.Rb6+ Kf5 8.Rd6 Kf4 9.Rf6+ Kg4 10.Ke5 Kg5 11.Rb6 Kg4 12.Rb3 Kg5 13.Rg3+ Kh4 14.Kf4 Kh5 15.Rg7 Kh6
  +-  (7.74)   Depth: 27/37   00:00:53  107mN
1.Rb6+ Kd5 2.Rxh6 Kd4 3.Kb3 Ke4 4.Rh7 Kd3 5.Rh5 Kd4 6.Rb5 Kd3 7.Rb4 Ke2 8.Kc3 Ke3 9.Ra4 Ke2 10.Re4+ Kf3 11.Kd3 Kg2 12.Re3 Kf2 13.Ke4 Kg2 14.Rf3 Kh2 15.Kd3 Kg2
  +-  (#44)   Depth: 28/39   00:41:56  5454mN

(, AMD 25.12.2007)

Zappa Mexico is much more accurate. It finds the mate in 18 moves. Look:

Analysis by Zappa Mexico :

1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kd6 5.Rh8 Ke6 6.Ke4 Ke7 7.Ke5
  +-  (3.57)   Depth: 10/25   00:00:01  195kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kd6 5.Rh8 Ke6 6.Ke4 Ke7 7.Ke5
  +-  (3.57)   Depth: 10/25   00:00:01  206kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kd5 5.Rd4+ Ke5 6.Re4+ Kd5 7.Rd4+
  +-  (3.58)   Depth: 11/25   00:00:01  337kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kd5 5.Rd4+ Ke5 6.Re4+ Kd5 7.Rd4+
  +-  (3.58)   Depth: 11/25   00:00:01  352kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Kc3 Kd5 4.Kd3 Ke5 5.Rh4 Kd5 6.Rh5+ Ke6 7.Kd4 Kf6 8.Rh6+ Kg5 9.Re6 Kf4 10.Rf6+ Kg5 11.Rf8 Kg4 12.Re8 Kf3 13.Rf8+ Kg3 14.Re8 Kf3
  +-  (3.63)   Depth: 12/25   00:00:02  702kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Kc3 Kd5 4.Kd3 Ke5 5.Rh4 Kd5 6.Rh5+ Ke6 7.Kd4 Kf6 8.Rh6+ Kg5 9.Re6 Kf4 10.Rf6+ Kg5 11.Rf8 Kg4 12.Re8 Kf3 13.Rf8+ Kg3 14.Re8 Kf3
  +-  (3.63)   Depth: 12/25   00:00:02  723kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Kf5 4.Kd3 Kg5 5.Re4 Kf6 6.Kd4 Kg5 7.Ke5 Kg6 8.Rh4 Kf7 9.Rh7+ Ke8 10.Rc7
  +-  (3.64)   Depth: 13/25   00:00:03  1053kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Kf5 4.Kd3 Kg5 5.Re4 Kf6 6.Kd4 Kg5 7.Ke5 Kg6 8.Rh4 Kf7 9.Rh7+ Ke8 10.Rc7
  +-  (3.64)   Depth: 13/25   00:00:03  1083kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Kf5 4.Kd3 Kg5 5.Re4 Kf6 6.Kd4 Kf5 7.Kd5 Kf6 8.Rf4+ Kg5 9.Rf7 Kg6 10.Rf8 Kg5 11.Ke5 Kg6 12.Rf6+ Kg5 13.Rf8
  +-  (3.67)   Depth: 14/25   00:00:04  1641kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Kf5 4.Kd3 Kg5 5.Re4 Kf6 6.Kd4 Kf5 7.Kd5 Kf6 8.Rf4+ Kg5 9.Rf7 Kg6 10.Rf8 Kg5 11.Ke5 Kg6 12.Rf6+ Kg5 13.Rf8
  +-  (3.67)   Depth: 14/25   00:00:04  1686kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Kf5 4.Kd3 Kg5 5.Rc4 Kf5 6.Kd4 Ke6 7.Rc6+ Kf5 8.Rd6 Kf4 9.Rf6+ Kg5 10.Ke5 Kh4 11.Rf8
  +-  (3.68)   Depth: 15/25   00:00:06  2656kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Kf5 4.Kd3 Kg5 5.Rc4 Kf5 6.Kd4 Ke6 7.Rc6+ Kf5 8.Rd6 Kf4 9.Rf6+ Kg5 10.Ke5 Kh4 11.Rf8
  +-  (3.68)   Depth: 15/25   00:00:06  2723kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Kc3 Ke5 4.Kc4 Ke4 5.Re6+ Kf5 6.Kd5 Kf4 7.Kd4 Kg5 8.Ke4 Kg4 9.Rg6+ Kh5 10.Rg7 Kh4 11.Rf7 Kg5 12.Rf8 Kg6 13.Re8 Kf7 14.Rd8 Kg6 15.Ke5 Kf7 16.Rd7+ Kg6
  +-  (3.71)   Depth: 16/29   00:00:16  5316kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Kc3 Ke5 4.Kc4 Ke4 5.Re6+ Kf5 6.Kd5 Kf4 7.Kd4 Kf3 8.Re7 Kf2 9.Ke4 Ke2 10.Rf7 Kd1 11.Kd3 Kc1
  +-  (3.71)   Depth: 16/29   00:00:17  5425kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Kc3 Ke5 4.Rh5+ Ke4 5.Rc5 Kf3 6.Kd4 Kf4 7.Kd3 Kf3 8.Rf5+ Kg3 9.Rf6 Kh3 10.Ke4 Kg4 11.Rg6+ Kh4 12.Rg7 Kh3 13.Kd5 Kh4 14.Ke4
  +-  (3.74)   Depth: 17/29   00:00:22  7956kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Kc3 Ke5 4.Rh5+ Ke4 5.Rc5 Kf3 6.Kd4 Kf4 7.Kd3 Kf3 8.Rf5+ Kg3 9.Rf6 Kh3 10.Ke4 Kg4 11.Rg6+ Kh4 12.Rg7 Kh3 13.Kd5 Kh4 14.Ke4
  +-  (3.74)   Depth: 17/29   00:00:22  8110kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh5 Kd4 4.Kd2 Ke4 5.Kc3 Kf3 6.Kd3 Kg4 7.Rd5 Kf4 8.Rb5 Kf3 9.Rb4 Kf2 10.Re4 Kf3 11.Ra4 Kf2 12.Rf4+ Kg3 13.Ke3 Kg2 14.Rg4+ Kh3 15.Kf3 Kh2 16.Rd4 Kg1
  +-  (#19)   Depth: 18/32   00:01:20  35262kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh5 Kd4 4.Kd2 Ke4 5.Kc3 Kf3 6.Kd3 Kg4 7.Rd5 Kf4 8.Rb5 Kf3 9.Rb4 Kf2 10.Re4 Kf3 11.Ra4 Kf2 12.Rf4+ Kg3 13.Ke3 Kg2 14.Rg4+ Kh3 15.Kf3 Kh2 16.Rd4 Kg1
  +-  (#19)   Depth: 18/32   00:01:20  35450kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh5 Kd4 4.Kd2 Ke4 5.Kc3 Kf3 6.Kd3 Kg4 7.Rd5 Kf4 8.Rb5 Kf3 9.Rb4 Kf2 10.Re4 Kf3 11.Ra4 Kf2 12.Rf4+ Kg3 13.Ke3 Kg2 14.Rg4+ Kh3 15.Kf3 Kh2 16.Rd4 Kg1
  +-  (#19)   Depth: 19/33   00:02:04  52973kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh5 Kd4 4.Kd2 Ke4 5.Kc3 Kf3 6.Kd3 Kg4 7.Rd5 Kf4 8.Rb5 Kf3 9.Rb4 Kf2 10.Re4 Kf3 11.Ra4 Kf2 12.Rf4+ Kg3 13.Ke3 Kg2 14.Rg4+ Kh3 15.Kf3 Kh2 16.Rd4 Kg1
  +-  (#19)   Depth: 19/33   00:02:04  53163kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh5 Kd4 4.Kd2 Ke4 5.Kc3 Kf3 6.Rf5+ Ke4 7.Rf1 Ke5 8.Kc4 Ke4 9.Kc5 Ke3 10.Rb1 Ke4 11.Rb4+ Kf3 12.Kd4 Kf2 13.Ke4 Ke2 14.Kf5 Kf2 15.Ra4 Ke2 16.Ra2+ Kf1
  +-  (#18)   Depth: 20/33   00:04:48  116mN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh5 Kd4 4.Kd2 Ke4 5.Kc3 Kf3 6.Rf5+ Ke4 7.Rf1 Ke5 8.Kc4 Ke4 9.Kc5 Ke3 10.Rb1 Ke4 11.Rb4+ Kf3 12.Kd4 Kf2 13.Ke4 Ke2 14.Kf5 Kf2 15.Ra4 Ke2 16.Ra2+ Kf1
  +-  (#18)   Depth: 20/33   00:04:52  117mN
1.Rb6+ Kd5 2.Rxh6 Ke5 3.Kd3 Kd5 4.Rh5+ Ke6 5.Kd4 Kf6 6.Ke4 Ke6 7.Rh6+ Kd7 8.Kd4 Ke7 9.Kd5 Kd7 10.Rh7+ Ke8 11.Ke5 Kf8 12.Kd5 Ke8
  +-  (#18)   Depth: 21/34   00:15:22  292mN
1.Rb6+ Kd5 2.Rxh6 Ke5 3.Kd3 Kd5 4.Rh5+ Ke6 5.Kd4 Kf6 6.Ke4 Ke6 7.Rh6+ Kd7 8.Kd4 Kc8 9.Rd6 Kb7 10.Kc5 Kc7 11.Rd5 Kb7 12.Re5 Kc7 13.Re7+ Kd8 14.Re1 Kd7 15.Re4 Kc7 16.Re5 Kd7
  +-  (#18)   Depth: 21/34   00:15:24  292mN

(, AMD 25.12.2007)

Regards,
Gaмßito.
Parent - By richbell (**) Date 2007-12-26 11:24
Any output for Rybka?
Parent - - By Dadi Jonsson (Silver) Date 2007-12-26 11:29
Rybka 2.3.2a mp:

[(+6.39)]  d=15  1.Rb6 Kf5 2.Rxh6 Ke4 3.Rh4 Kf5 4.Kd3 Kg5 5.Ra4 Kf5 6.Ra5 Ke6 7.Kd4 Kf6 (0:00.42)
[(+6.33)]  d=14  1.Rb6 Kf5 2.Rxh6 Ke4 3.Rh4 Ke5 4.Kd3 Ke6 5.Rh5 Kd6 6.Ke4 (0:00.18)
[(+6.31)]  d=13  1.Rb6 Kf5 2.Rxh6 Ke4 3.Rh4 Ke5 4.Kd3 Kf5 5.Rh5 (0:00.06)
[(+6.31)]  d=12  1.Rb6 Kf5 2.Rxh6 Ke4 3.Rh4 Ke5 4.Kd3 Kf5 5.Rh5 Kg4 6.Rb5 Kf4 7.Kd4 (0:00.03)
[(+6.31)]  d=11  1.Rb6 Kf5 2.Rxh6 Ke4 3.Rh4 Ke5 4.Kd3 Kf5 5.Rh5 Kf4 6.Rb5 Kf3 (0:00.01)
[(+6.28)]  d=10  1.Rb6 Kf5 2.Rxh6 Ke4 3.Rh4 Ke5 4.Kd3 Kf5 5.Rh5 Kf4 6.Rb5 (0:00.00)
[(+6.23)]  d=9  1.Rb6 Kf5 2.Rxh6 Ke4 3.Rh4 Ke5 4.Kd3 Kf5 (0:00.00)
[(+6.23)]  d=8  1.Rb6 Kf5 2.Rxh6 Kg5 3.Rc6 Kf5 (0:00.00)
[(+6.21)]  d=7  1.Rb6 Kf5 2.Rxh6 Kg5 3.Rc6 (0:00.00)
[(+6.18)]  d=6  1.Rb6 Kf5 2.Rxh6 Ke4 (0:00.00)
[(+6.10)]  d=5  1.Rb6 Kf5 2.Rxh6 (0:00.00)
Parent - - By richbell (**) Date 2007-12-26 16:10
Hmm, wonder how long it takes to find a mate. Could some expert explain what am i missing here, that takes so long for an engine to find a mate? I thought Rybka's knowledge is far superior for this kind of trivial problem.
Parent - By Vempele (Silver) Date 2007-12-26 18:02

> Hmm, wonder how long it takes to find a mate. Could some expert explain what am i missing here, that takes so long for an engine to find a mate? I thought Rybka's knowledge is far superior for this kind of trivial problem.


Knowledge is meaningless in positions like this. You just have to search deep to find the mate and prove the opponent can't escape it.

Besides, why would Rybka even have any special knowledge about the KRk endgame? It's trivially handled by tablebases. Probably all she knows is that she should drive the king to the edge.
Parent - - By Gaмßito (****) Date 2007-12-26 19:47
Vempele is right.  Programs need to search enough deep here to find the mate.

Rybka does not have any special knowledge to solve this kind of position. Anyway, it will be able to win soon or later although it is not able to find the mate just from this position.

I let Rybka thinking, but after 1 hour it cannot see the mate. In fact, Rybka is unable to search very deeply here.
Now it has more than 3 hours and it does not advance toward the following ply. 

Analysis by Rybka 2.3.2a 32-bit :

1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rh1 Kf5 4.Kd3 Ke5 5.Rh5+ Kf4 6.Kd4
  +-  (6.10)   Depth: 5   00:00:00
1.Rb6+ Kf5 2.Rxh6 Ke4 3.Rh4+ Kd5 4.Kd3 Ke5 5.Rh5+ Kf4 6.Kd4
  +-  (6.18)   Depth: 6   00:00:00  5kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rc6 Kf5 4.Kd3 Kf4 5.Kd4 Kf5 6.Rc5+ Kf4
  +-  (6.21)   Depth: 7   00:00:00  16kN
1.Rb6+ Kf5 2.Rxh6 Kg5 3.Rc6 Kf5 4.Kd3 Ke5 5.Rc5+ Kf4 6.Kd4 Kg4 7.Rc1
  +-  (6.23)   Depth: 8   00:00:00  33kN
1.Rb6+ Kf5 2.Rxh6 Ke4 3.Rh4+ Kd5 4.Kd3 Ke5 5.Rh5+ Kf4 6.Ra5 Kg3 7.Ke4 Kg4 8.Rc5 Kg3
  +-  (6.23)   Depth: 9   00:00:01  132kN
1.Rb6+ Kf5 2.Rxh6 Ke4 3.Rh4+ Kd5 4.Kd3 Ke5 5.Rh5+ Kf4 6.Ra5 Kf3 7.Ra4 Kg3 8.Ke4
  +-  (6.28)   Depth: 10   00:00:02  300kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kf5 5.Rh5+ Kg4 6.Rc5 Kf4 7.Kd4 Kf3 8.Ke5
  +-  (6.28)   Depth: 11   00:00:10  1481kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kf5 5.Rh5+ Kg4 6.Rc5 Kf4 7.Kd4 Kf3 8.Ke5
  +-  (6.31)   Depth: 12   00:00:16  2326kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kf5 5.Rh5+ Kg4 6.Rc5 Kf4 7.Kd4 Kf3 8.Rf5+
  +-  (6.31)   Depth: 13   00:00:27  3761kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kf5 5.Rh5+ Kg4 6.Rd5 Kf4 7.Kd4 Kf3 8.Ke5 Ke3 9.Kf5 Kf3 10.Rd3+ Ke2 11.Ke4
  +-  (6.32)   Depth: 14   00:00:54  7790kN
1.Rb6+ Kd5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kf5 5.Rh5+ Kg4 6.Rd5 Kf4 7.Kd4 Kf3 8.Rf5+ Kg3 9.Ke4 Kg4 10.Rc5 Kg3 11.Rg5+ Kh4 12.Rg6 Kh5 13.Kf5
  +-  (6.39)   Depth: 15   00:02:19  21745kN
1.Rb6+ Ke5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kf5 5.Rh5+ Kg4 6.Rd5 Kf4 7.Kd4 Kf3 8.Rf5+ Kg3 9.Ke4 Kg4 10.Rc5 Kg3 11.Rg5+ Kf2 12.Rg6 Ke1 13.Rg2 Kd1 14.Rf2 Ke1 15.Ra2 Kd1 16.Rf2 Ke1
  +-  (6.47)   Depth: 16   00:10:44  105mN
1.Rb6+ Ke5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kf5 5.Rh5+ Kg4 6.Rd5 Kf4 7.Kd4 Kf3 8.Rf5+ Kg3 9.Ke4 Kg4 10.Rc5 Kg3 11.Rg5+ Kf2 12.Rg6 Ke1 13.Rg2 Kd1 14.Ke5 Ke1 15.Rc2
  +-  (6.47)   Depth: 17   00:31:45  290mN
1.Rb6+ Ke5 2.Rxh6 Ke4 3.Rh4+ Ke5 4.Kd3 Kf5 5.Rh5+ Kg4 6.Rd5 Kf4 7.Kd4 Kf3 8.Rf5+ Kg3 9.Ke4 Kg4 10.Rc5 Kg3 11.Rg5+ Kf2 12.Rg6 Ke1 13.Rg2 Kd1 14.Ke5 Ke1 15.Rc2
  +-  (6.49)   Depth: 18   01:06:44  628mN

(, AMD 26.12.2007)

Regards,
Gaмßito.
Parent - - By richbell (**) Date 2007-12-27 09:16
Interesting... ok, Point taken. As long as Rb6+ is the next move, finding a mate or not doesn't make a difference.
Parent - By M ANSARI (*****) Date 2007-12-27 10:03
I think these sort of positions are meaningless today since these simple positions are immediately handled by EGTB's.  4 piece EGTB's take a minisculte amount of space on today's hardware and you would find that almost everyone has at least 5 piece EGTB's.  I think engine authors could easily write software that could immediately find a mate in such a position, but why bother adding additional code when the "fix" is already there.  I think we should all assume that 5 piece EGTB's are a given and look for problems that occur outside that realm.  I know for some they would like to see their engine solve problems they consider trivial without the aid of EGTB's, but really I don't see this as an issue to worry about because it would take milliseconds for an engine with EGTB's to find a mate.
Parent - - By Vasik Rajlich (Silver) Date 2007-12-27 13:04
This isn't really a target for programmers. The goal in chess is to get good positions, and being a rook up is pretty good :)

Vas
Parent - By richbell (**) Date 2007-12-27 16:14
Agreed, agreed. :-)
Up Topic Rybka Support & Discussion / Rybka Discussion / Simple Endgame knowledge!

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