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Up Topic Rybka Support & Discussion / Rybka Discussion / Rybka misses simple mate in 2
- - By Fulcrum2000 (****) [nl] Date 2010-06-06 00:04 Edited 2010-06-06 00:21
See position below. Rybka does not see both legal white moves (g3 and g4) lead to a mate in 2.
(5 and some 6-men EGTB loaded, but no kbpkpp)

8/8/8/8/7p/7P/6P1/5kbK w - - 0 96


96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 51   00:00:00  1kN, tb=443
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 52   00:00:00  1kN, tb=557
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 53   00:00:00  1kN, tb=727
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 54   00:00:00  2kN, tb=912
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 55   00:00:00  2kN, tb=1190
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 56   00:00:00  4kN, tb=1504
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 57   00:00:00  6kN, tb=1974
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 58   00:00:00  58kN, tb=2756
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 59   00:00:00  116kN, tb=3847
96.g3 Kf2 97.gxh4
  =  (0.00)   Depth: 59   00:00:01  189kN, tb=4433

After playing the move Rybka gets awake and sees it's game over:

8/8/8/8/7p/6PP/8/5kbK b - - 0 96


96...hxg3 97.h4 g2#
  -+  (-#2)   Depth: 6   00:00:00  0kN, tb=9
96...hxg3 97.h4 g2#
  -+  (-#2)   Depth: 7   00:00:00  0kN, tb=10
96...hxg3 97.h4 g2#
  -+  (-#2)   Depth: 8   00:00:00  0kN, tb=11
96...hxg3 97.h4 g2#
  -+  (-#2)   Depth: 9   00:00:00  0kN, tb=12
96...hxg3 97.h4 g2#
  -+  (-#2)   Depth: 10   00:00:00  0kN, tb=13
96...hxg3 97.h4 g2#
  -+  (-#2)   Depth: 11   00:00:00  0kN, tb=15
96...hxg3 97.h4 g2#
Parent - - By Fulcrum2000 (****) [nl] Date 2010-06-06 00:14
BTW Position is from a playchess game :

[Event "Crawly's Suizo 16+0 11 rnds 05-06-2010"]
[Site "playchess.com"]
[Date "2010.06.06"]
[Round "11"]
[White "Argentum, Deep Rybka 4 SSE42 "]
[Black "Highendman, Deep Rybka 4 SSE42 "]
[Result "0-1"]
[ECO "C90"]
[WhiteElo "2583"]
[BlackElo "2654"]
[PlyCount "194"]
[EventDate "2010.06.06"]
[EventType "swiss (rapid)"]
[TimeControl "960"]

1. e4 {[%eval 0,0] [%emt 0:00:00]} e5 {[%eval 0,0] [%emt 0:00:00]} 2. Nf3 {
[%eval 0,0] [%emt 0:00:00]} Nc6 {[%eval 0,0] [%emt 0:00:00]} 3. Bb5 {[%eval 0,
0] [%emt 0:00:00]} a6 {[%eval 0,0] [%emt 0:00:00]} 4. Ba4 {[%eval 0,0] [%emt 0:
00:00]} Nf6 {[%eval 0,0] [%emt 0:00:00]} 5. O-O {[%eval 0,0] [%emt 0:00:00]}
Be7 {[%eval 0,0] [%emt 0:00:00]} 6. Re1 {[%eval 0,0] [%emt 0:00:00]} b5 {
[%eval 0,0] [%emt 0:00:00]} 7. Bb3 {[%eval 0,0] [%emt 0:00:00]} d6 {[%eval 0,0]
[%emt 0:00:00]} 8. c3 {[%eval 0,0] [%emt 0:00:00]} Na5 {[%eval -25,20] [%emt 0:
01:19]} 9. Bc2 {[%eval 0,0] [%emt 0:00:00]} c5 {[%eval -24,22] [%emt 0:00:35]}
10. d4 {[%eval 0,0] [%emt 0:00:00]} Qc7 {[%eval -24,21] [%emt 0:00:19]} 11. a4
{[%eval 0,0] [%emt 0:00:00]} c4 {[%eval -9,20] [%emt 0:01:21]} 12. Nbd2 {
[%eval 11,19] [%emt 0:00:54]} Bb7 {[%eval -8,20] [%emt 0:01:19] Argentum
reconnected.} 13. h3 {[%eval 21,19] [%emt 0:00:48]} O-O {[%eval -12,20] [%emt
0:01:16]} 14. Nf1 {[%eval 21,19] [%emt 0:00:00]} Rfe8 {[%eval -9,18] [%emt 0:
00:30] (Tfd8)} 15. Ng3 {[%eval 23,18] [%emt 0:01:18]} g6 {[%eval -10,18] [%emt
0:00:28]} 16. Bg5 {[%eval 22,18] [%emt 0:00:00]} Reb8 {[%eval -9,17] [%emt 0:
00:17] (Tab8)} 17. Qd2 {[%eval 23,18] [%emt 0:00:54]} Rd8 {[%eval -3,18] [%emt
0:00:28]} 18. Ra3 {[%eval 23,18] [%emt 0:00:00]} Bc6 {[%eval -5,17] [%emt 0:00:
49] (Te8)} 19. Qe3 {[%eval 26,17] [%emt 0:00:37]} Rdb8 {[%eval 0,19] [%emt 0:
00:21] (bxa4)} 20. axb5 {[%eval 26,19] [%emt 0:00:39]} axb5 {[%eval 0,21]
[%emt 0:00:00]} 21. Rea1 {[%eval 26,19] [%emt 0:00:17]} Bb7 {[%eval 1,18]
[%emt 0:00:47]} 22. R3a2 {[%eval 30,20] [%emt 0:00:00]} Nc6 {[%eval 0,20]
[%emt 0:00:16]} 23. b4 {[%eval 36,19] [%emt 0:00:00]} Rxa2 {[%eval 9,18] [%emt
0:00:12]} 24. Rxa2 {[%eval 36,21] [%emt 0:00:00]} Ra8 {[%eval 3,20] [%emt 0:00:
19] (exd4)} 25. Rxa8+ {[%eval 34,21] [%emt 0:00:51]} Bxa8 {[%eval 0,24] [%emt
0:00:00]} 26. d5 {[%eval 27,20] [%emt 0:00:32]} Nb8 {[%eval 0,24] [%emt 0:00:
00]} 27. Bh6 {[%eval 27,20] [%emt 0:00:15]} Ne8 {[%eval 0,22] [%emt 0:00:42]
(Ab7)} 28. Qc1 {[%eval 23,21] [%emt 0:00:37]} Nd7 {[%eval -5,21] [%emt 0:00:18]
} 29. Nf1 {[%eval 23,20] [%emt 0:00:02]} Bf8 {[%eval -7,20] [%emt 0:00:13]
(Ab7)} 30. Be3 {[%eval 23,20] [%emt 0:00:34]} Bb7 {[%eval -7,23] [%emt 0:00:00]
(Dd8)} 31. N3h2 {[%eval 22,20] [%emt 0:00:44]} Nef6 {[%eval -7,22] [%emt 0:00:
23]} 32. Ng3 {[%eval 23,21] [%emt 0:00:00]} Bc8 {[%eval -8,21] [%emt 0:00:12]
(Dd8)} 33. Qa3 {[%eval 21,22] [%emt 0:00:21]} Be7 {[%eval -8,21] [%emt 0:00:12]
(Rg7)} 34. Nf3 {[%eval 21,21] [%emt 0:00:45]} Kh8 {[%eval -14,21] [%emt 0:00:
00] (Db7)} 35. Qc1 {[%eval 20,19] [%emt 0:00:20]} Bd8 {[%eval -16,20] [%emt 0:
00:33] (Db7)} 36. Bd1 {[%eval 12,19] [%emt 0:00:17]} Qb8 {[%eval -21,19] [%emt
0:00:10] (Db7)} 37. Bg5 {[%eval 12,21] [%emt 0:00:24]} Bb6 {[%eval -21,21]
[%emt 0:00:09]} 38. Nh2 {[%eval 9,20] [%emt 0:00:08]} Qa7 {[%eval -21,21]
[%emt 0:00:09] (Da8)} 39. Qb2 {[%eval 9,22] [%emt 0:00:21]} Kg7 {[%eval -21,22]
[%emt 0:00:00]} 40. Bc1 {[%eval 9,21] [%emt 0:00:07]} Bb7 {[%eval -21,21]
[%emt 0:00:08] (Cg8)} 41. Nf3 {[%eval 9,20] [%emt 0:00:16]} Qa6 {[%eval -21,22]
[%emt 0:00:00] (Da8)} 42. Bg5 {[%eval 9,20] [%emt 0:00:13]} Qa8 {[%eval -21,22]
[%emt 0:00:00]} 43. Bd2 {[%eval 0,20] [%emt 0:00:35]} Kh8 {[%eval -21,20]
[%emt 0:00:11] (Da7)} 44. Bc1 {[%eval 8,20] [%emt 0:00:17]} Qf8 {[%eval -21,22]
[%emt 0:00:00] (Rg7)} 45. Ne1 {[%eval 8,19] [%emt 0:00:09]} Ng8 {[%eval -37,17]
[%emt 0:00:06]} 46. Bg4 {[%eval 0,19] [%emt 0:00:08]} f5 {[%eval -45,19] [%emt
0:00:00] (Cdf6)} 47. exf5 {[%eval -16,17] [%emt 0:00:02]} h5 {[%eval -45,19]
[%emt 0:00:00] (Cgf6)} 48. Bd1 {[%eval -27,18] [%emt 0:00:15]} h4 {[%eval -51,
20] [%emt 0:00:00]} 49. Ne4 {[%eval -35,19] [%emt 0:00:34]} gxf5 {[%eval -50,
18] [%emt 0:00:03]} 50. Ng5 {[%eval -35,20] [%emt 0:00:00]} Qg7 {[%eval -50,18]
[%emt 0:00:03] (Axd5)} 51. Qc2 {[%eval -35,17] [%emt 0:00:06]} Ne7 {[%eval -79,
18] [%emt 0:00:10] (e4)} 52. Nef3 {[%eval -49,18] [%emt 0:00:05]} Bxd5 {[%eval
-78,19] [%emt 0:00:00]} 53. Qe2 {[%eval -49,18] [%emt 0:00:02]} f4 {[%eval -81,
19] [%emt 0:00:08] (Cf6)} 54. Kf1 {[%eval -50,18] [%emt 0:00:07]} Bc7 {[%eval
-83,17] [%emt 0:00:08] (Cf6)} 55. Ne4 {[%eval -57,15] [%emt 0:00:04]} Nf6 {
[%eval -93,18] [%emt 0:00:00]} 56. Nxf6 {[%eval -69,17] [%emt 0:00:05]} Qxf6 {
[%eval -97,19] [%emt 0:00:00]} 57. Qa2 {[%eval -67,17] [%emt 0:00:02]} Bd8 {
[%eval -97,19] [%emt 0:00:00]} 58. Qa7 {[%eval -68,17] [%emt 0:00:03]} Be4 {
[%eval -97,18] [%emt 0:00:00]} 59. Ne1 {[%eval -70,17] [%emt 0:00:08]} Nd5 {
[%eval -91,17] [%emt 0:00:05]} 60. Bd2 {[%eval -66,18] [%emt 0:00:00]} Bg6 {
[%eval -103,16] [%emt 0:00:02]} 61. Bc2 {[%eval -66,16] [%emt 0:00:01]} e4 {
[%eval -102,15] [%emt 0:00:01]} 62. f3 {[%eval -89,15] [%emt 0:00:01]} e3 {
[%eval -118,15] [%emt 0:00:01] (Ce3+)} 63. Bxg6 {[%eval -83,12] [%emt 0:00:01]}
Nc7 {[%eval -118,16] [%emt 0:00:01]} 64. Bxe3 {[%eval -67,14] [%emt 0:00:01]}
fxe3 {[%eval -118,16] [%emt 0:00:00]} 65. Qb8 {[%eval -82,15] [%emt 0:00:01]}
Nd5 {[%eval -123,16] [%emt 0:00:09] (e2+)} 66. Qxb5 {[%eval -119,15] [%emt 0:
00:05]} e2+ {[%eval -136,17] [%emt 0:00:00]} 67. Kg1 {[%eval -104,15] [%emt 0:
00:00]} Nxc3 {[%eval -136,17] [%emt 0:00:00]} 68. Qxc4 {[%eval -100,15] [%emt
0:00:00]} Bb6+ {[%eval -184,17] [%emt 0:00:01]} 69. Kh1 {[%eval -122,17] [%emt
0:00:00]} Qd4 {[%eval -184,18] [%emt 0:00:00] (Rg7)} 70. Qxd4+ {[%eval -122,16]
[%emt 0:00:01]} Bxd4 {[%eval -192,21] [%emt 0:00:00]} 71. Bd3 {[%eval -131,19]
[%emt 0:00:01]} Bf2 {[%eval -200,23] [%emt 0:00:00] (Rg7)} 72. Nc2 {[%eval
-131,16] [%emt 0:00:03]} e1=Q+ {[%eval -200,24] [%emt 0:00:00] (Rg7)} 73. Nxe1
{[%eval -186,17] [%emt 0:00:00]} Bxe1 {[%eval -200,24] [%emt 0:00:00]} 74. Kg1
{[%eval -186,20] [%emt 0:00:00]} Bg3 {[%eval -201,24] [%emt 0:00:01] (d5)} 75.
b5 {[%eval -186,21] [%emt 0:00:06]} Kg7 {[%eval -228,22] [%emt 0:00:00] (d5)}
76. b6 {[%eval -225,21] [%emt 0:00:03]} Kf7 {[%eval -270,19] [%emt 0:00:00]
(d5)} 77. b7 {[%eval -240,18] [%emt 0:00:04]} d5 {[%eval -270,19] [%emt 0:00:
00]} 78. f4 {[%eval -240,19] [%emt 0:00:01]} Bxf4 {[%eval -310,18] [%emt 0:00:
00]} 79. Kf2 {[%eval -240,18] [%emt 0:00:00]} Ke6 {[%eval -309,18] [%emt 0:00:
00]} 80. Kf3 {[%eval -266,19] [%emt 0:00:00]} Bg3 {[%eval -332,19] [%emt 0:00:
00]} 81. Ke3 {[%eval -266,18] [%emt 0:00:03]} Ne4 {[%eval -374,19] [%emt 0:00:
01] (Ae5)} 82. Bxe4 {[%eval 0,15] [%emt 0:00:00]} dxe4 {[%eval -1312,14] [%emt
0:00:01]} 83. Kxe4 {[%eval 0,19] [%emt 0:00:00]} Kd7 {[%eval -32707,14] [%emt
0:00:00]} 84. Ke3 {[%eval 0,18] [%emt 0:00:00]} Kc6 {[%eval -32711,22] [%emt 0:
00:04]} 85. Ke2 {[%eval 0,21] [%emt 0:00:00]} Kxb7 {[%eval -32715,22] [%emt 0:
00:01]} 86. Kf1 {[%eval 0,26] [%emt 0:00:00]} Kc6 {[%eval -32721,59] [%emt 0:
00:00] (Ah2)} 87. Kg1 {[%eval 0,25] [%emt 0:00:03]} Kd5 {[%eval -32729,59]
[%emt 0:00:00] (Rb6)} 88. Kf1 {[%eval 0,26] [%emt 0:00:01]} Ke4 {[%eval -32731,
59] [%emt 0:00:00] (Ae5)} 89. Kg1 {[%eval 0,36] [%emt 0:00:01]} Kf4 {[%eval
-32747,59] [%emt 0:00:00]} 90. Kh1 {[%eval 0,37] [%emt 0:00:01]} Ke3 {[%eval
-32749,59] [%emt 0:00:00] (Re5)} 91. Kg1 {[%eval 0,26] [%emt 0:00:00]} Ke2 {
[%eval -32751,59] [%emt 0:00:00] (Ae5)} 92. Kh1 {[%eval 0,28] [%emt 0:00:00]}
Ke1 {[%eval -32753,59] [%emt 0:00:00] (Ab8)} 93. Kg1 {[%eval 0,23] [%emt 0:00:
00]} Bf2+ {[%eval -32755,59] [%emt 0:00:00]} 94. Kh2 {[%eval 0,35] [%emt 0:00:
02]} Kf1 {[%eval -32759,59] [%emt 0:00:00] (Re2)} 95. Kh1 {[%eval 0,41] [%emt
0:00:02]} Bg1 {[%eval -32761,59] [%emt 0:00:00] (Ag3)} 96. g4 {[%eval 0,56]
[%emt 0:00:01]} hxg3 {[%eval -32763,59] [%emt 0:00:00]} 97. h4 {[%eval -32765,
0] [%emt 0:00:00]} g2# {[%eval -32765,0] [%emt 0:00:00] (Lag: Av=0.43s, max=1.
0s)} 0-1
Parent - - By sarciness (***) [cn] Date 2010-06-06 04:57
Wow, that's appauling! I hope for the sake of R4 customers that Vas does something to fix these bugs which seem to be popping up. If he doesn't, I won't be making the purchase.
Parent - By UltimateChess (**) [cz] Date 2010-06-06 14:35
Yeah, thanks for posting. This is really scary not to see mate in 2 (I am willing to forgive not seeing some mate in 3). This is ridiculous that top chess entity in the Universe doesnt see what every child can see easily....
Shame on you Rybka, shame. Actually now I begin to desire to Rybka beeing kicked out of her throne. I am looking forward to it.
Parent - - By Legendary (***) Date 2010-06-06 05:12
Those critters (bugs) are crawling all throughout Rybka 4's code, I see.
Are you sure that your hash is not encumbered?
Parent - By Fulcrum2000 (****) [nl] Date 2010-06-06 11:27
Yes, you can try the position yourself and see what your R4 has to say about it.
Parent - By Richard Vida (**) Date 2010-06-07 23:44
Let's hope that there are no rybkas throughout Critter's code :)

Richard
Parent - By appletree (**) [sk] Date 2010-06-06 09:29
This is disturbing. I wonder what could be causing it. I see that R4 now understands blind bishop, e.g. if we remove all the white pawns and place black bishop to e.g. b6 then she correctly evals it as dead draw (without EGTB). Maybe that mate overlooking has something to do with it, she could misunderstand that once the black pawn moves to g file there are absolutely no drawing chances at all. Eeven if there was no immediate mate then still black g-pawn queens much faster then white's - I can not think of any other explanation why R4 would overlook it (except maybe she thinks that position after hxg3 is a stalemate - that would also give dead equal score - but this seems quite unlikely)
Parent - By mikal (**) [us] Date 2010-06-06 00:16
My Rybka 3 evaluates it as mate in 3, it might be wrong count but still it's at least mate not a 0.00 eval. Maybe this is the eval strength cap of Rybka 4, it does seem to let go of wins and turn them into draws.
Parent - By InspectorGadget (*****) [za] Date 2010-06-06 06:44
From Rybka's point of view, that pawn is on the same file as the King, so there was no mate threat at all :-D
Parent - - By irulats (****) [ie] Date 2010-06-06 08:33
Chest UCI doesn't get this 1 either (at least not on my setup).
Parent - - By Permanent Brain (*****) Date 2011-09-02 15:04
No problem. Since this starts with a move of the losing side (the defender), we need to check "Defender Moves" in the engine options.

WinCHEST Ver.3.19i+, 08-Mar-2011
Options = -M32 -x -Z7 -eL -U -0 -5 -rS
Input file: STDIN
Reading job:
% created by ChestUCI Ver.5.2
W:  Kh1 Pg2 Ph3 (3)
B:  Kf1 Bg1 Ph4 (3)
FEN:
8/8/8/8/7p/7P/6P1/5kbK w - -

analysing (mate in 7 moves):
After g2g3 ...
  Solution (in 2 moves):
  h4g3

PV= h4g3 h3h4 g3g2
h4g3  h3h4  g3g2

end of solution tree (no duals except at top)
After g2g4 ...
  Solution (in 2 moves):
  h4g3

PV= h4g3 h3h4 g3g2
h4g3  h3h4  g3g2

end of solution tree (no duals except at top)
Time (virt) = 0.000 sec


Chest/-UCI gives the (identical) result for both legal white moves.
Parent - By irulats (****) [ie] Date 2011-09-02 18:05

> we need to check "Defender Moves" in the engine options.
>
>


Brilliant tip! Thanks.
Parent - - By Kapaun (****) [de] Date 2010-06-06 09:01 Edited 2010-06-06 09:20
Oops! Yes, that's a funny thing for sure. R3 finds it, by the way.

Edit: Using IDeA, R4 finds it, too.
Parent - By InspectorGadget (*****) [za] Date 2010-06-06 15:12

> R3 finds it, by the way.


Rybka 1.1 finds it, by the way :-D
Parent - By Lukas Cimiotti (Bronze) [de] Date 2010-06-06 09:50
This is what I get:

8/8/8/8/7p/7P/6P1/5kbK w - - 0 1


Analysis by Deep Rybka 4 SSE42 x64:

96.g3
  -+  (-#2)   Depth: 6   00:00:00  0kN, tb=18
96.g3
  -+  (-#2)   Depth: 7   00:00:00  0kN, tb=21
96.g3
  -+  (-#2)   Depth: 8   00:00:00  0kN, tb=23
96.g3
  -+  (-#2)   Depth: 9   00:00:00  0kN, tb=25
96.g3
  -+  (-#2)   Depth: 10   00:00:00  0kN, tb=27
96.g3
  -+  (-#2)   Depth: 11   00:00:00  0kN, tb=29
96.g3
  -+  (-#2)   Depth: 12   00:00:00  0kN, tb=32
96.g3
  -+  (-#2)   Depth: 13   00:00:00  0kN, tb=34
96.g3
  -+  (-#2)   Depth: 14   00:00:00  0kN, tb=36
96.g3
  -+  (-#2)   Depth: 15   00:00:00  0kN, tb=38
96.g3
  -+  (-#2)   Depth: 16   00:00:00  0kN, tb=41
96.g3
  -+  (-#2)   Depth: 17   00:00:00  0kN, tb=43
96.g3
  -+  (-#2)   Depth: 18   00:00:00  0kN, tb=45
96.g3
  -+  (-#2)   Depth: 19   00:00:00  0kN, tb=47
96.g3
  -+  (-#2)   Depth: 20   00:00:00  0kN, tb=49
96.g3
  -+  (-#2)   Depth: 21   00:00:00  0kN, tb=52
96.g3
  -+  (-#2)   Depth: 22   00:00:00  0kN, tb=54
96.g3
  -+  (-#2)   Depth: 23   00:00:00  0kN, tb=56
96.g3
  -+  (-#2)   Depth: 24   00:00:00  0kN, tb=58
96.g3
  -+  (-#2)   Depth: 25   00:00:00  0kN, tb=60
96.g3
  -+  (-#2)   Depth: 26   00:00:00  0kN, tb=63
96.g3
  -+  (-#2)   Depth: 27   00:00:00  0kN, tb=65
96.g3
  -+  (-#2)   Depth: 28   00:00:00  0kN, tb=67
96.g3
  -+  (-#2)   Depth: 29   00:00:00  0kN, tb=69
96.g3
  -+  (-#2)   Depth: 30   00:00:00  0kN, tb=72
96.g3
  -+  (-#2)   Depth: 31   00:00:00  0kN, tb=74
96.g3
  -+  (-#2)   Depth: 32   00:00:00  0kN, tb=76
96.g3
  -+  (-#2)   Depth: 33   00:00:00  0kN, tb=78
96.g3
  -+  (-#2)   Depth: 34   00:00:00  0kN, tb=80
96.g3
  -+  (-#2)   Depth: 35   00:00:00  0kN, tb=83
96.g3
  -+  (-#2)   Depth: 36   00:00:00  0kN, tb=85
96.g3
  -+  (-#2)   Depth: 37   00:00:00  0kN, tb=87
96.g3
  -+  (-#2)   Depth: 38   00:00:00  0kN, tb=89
96.g3
  -+  (-#2)   Depth: 39   00:00:00  0kN, tb=91
96.g3
  -+  (-#2)   Depth: 40   00:00:00  0kN, tb=94
96.g3
  -+  (-#2)   Depth: 41   00:00:00  0kN, tb=96
96.g3
  -+  (-#2)   Depth: 42   00:00:00  0kN, tb=98
96.g3
  -+  (-#2)   Depth: 43   00:00:00  0kN, tb=100
96.g3
  -+  (-#2)   Depth: 44   00:00:00  0kN, tb=103
96.g3
  -+  (-#2)   Depth: 45   00:00:00  0kN, tb=105
96.g3
  -+  (-#2)   Depth: 46   00:00:00  0kN, tb=107
96.g3
  -+  (-#2)   Depth: 47   00:00:00  0kN, tb=109
96.g3
  -+  (-#2)   Depth: 48   00:00:00  0kN, tb=111
96.g3
  -+  (-#2)   Depth: 49   00:00:00  0kN, tb=114
96.g3
  -+  (-#2)   Depth: 50   00:00:00  0kN, tb=116
96.g3
  -+  (-#2)   Depth: 51   00:00:00  0kN, tb=118
96.g3
  -+  (-#2)   Depth: 52   00:00:00  0kN, tb=120
96.g3
  -+  (-#2)   Depth: 53   00:00:00  0kN, tb=122
96.g3
  -+  (-#2)   Depth: 54   00:00:00  0kN, tb=125
96.g3
  -+  (-#2)   Depth: 55   00:00:00  0kN, tb=127
96.g3
  -+  (-#2)   Depth: 56   00:00:00  0kN, tb=129
96.g3
  -+  (-#2)   Depth: 57   00:00:00  0kN, tb=131
96.g3
  -+  (-#2)   Depth: 58   00:00:00  0kN, tb=134
96.g3
  -+  (-#2)   Depth: 59   00:00:00  0kN, tb=136
96.g3
  -+  (-#2)   Depth: 59   00:00:00  0kN, tb=137

But without tablebases I also get 0.00 :(
Parent - - By oudheusa (*****) [nl] Date 2010-06-06 15:21
Since Vas has a restday, plse allow me to reply for him:

oh well, it's such a rare position, it can't be regarded as a bug.

and you shouldn't play without tb's, i have told you over and over again.

:) :)
Parent - - By Vasik Rajlich (Silver) [pl] Date 2010-06-07 19:44
Well said! :)

Vas
Parent - By rav (*) [us] Date 2011-08-21 13:53
Chess is a game of rare positions.  That is well said.

Rationalizing that the position is not worthy of consideration because it is rare is absurd.  In fact if this is a position of difficulty that your engine can not solve then that theme can't be solved, anytime anywhere.  Clearly there is a bug, or at the very least a failure in programming that blinds the software to the solution.
Parent - By Permanent Brain (*****) Date 2011-09-02 15:07
No problem for R232a:

Rybka 2.3.2a:
   5  00:00            17  17.408  -M3  96.g4 hxg3 97.h4 g2+
   6  00:00            26  26.624  -M3  96.g4 hxg3 97.h4 g2+
(...)
  14  00:07       383.080  55.141  -M3  96.g4 hxg3 97.h4 g2+
Best move: g4, Value: -Mate in 3, Depth: 15, Time: 00:07.530, 393.216 Nodes, 54.678 N/sec.
- - By Moz (****) Date 2010-06-06 09:58
Adding to the mystery is the fact that sampled search appears to see the mate!

<-- info sample g2g4 h4g3 icp -8155 h3h4 g3g2

This sample is repeated endlessly in the log file.  Clearly a bug.
Parent - By Moz (****) Date 2010-06-06 10:05 Edited 2010-06-06 10:11
Clarification:  Sampled search only shows the mate when in multipv mode and only for g4 not g3 -- very strange!   It spots the mate for a split second before continuing with the search - the score is always 0.00 for both g3 and g4.

      <<-- info sample g2g3 h4g3 icp -8155 h3h4 g3g2
      <<-- info multipv 1 depth 36 score cp 0 time 2329 nodes 10191 nps 4375 tbhits 1994 pv g2g3 
      <<-- info multipv 2 depth 35 score cp 0 time 2017 nodes 8023 nps 3977 tbhits 1622 pv g2g4 h4g3 h3h4 g3g2
      <<-- info currmove g2g4 currmovenumber 2
      <<-- info sample g2g4 issearching
      <<-- info sample g2g4 h4g3 icp -8155 h3h4 g3g2
      <<-- info multipv 1 depth 36 score cp 0 time 2329 nodes 10191 nps 4375 tbhits 1994 pv g2g3
      <<-- info multipv 2 depth 36 score cp 0 time 2345 nodes 10196 nps 4347 tbhits 2127 pv g2g4 h4g3 h3h4 g3g2
      <<-- info depth 36 time 2345 nodes 10196 nps 4347 tbhits 2127
      <<-- info depth 37
- - By LHawk (*) [lt] Date 2010-06-06 15:59
8/8/8/8/7p/7P/4k1P1/6bK b - -

You can get nice analysis from some other engines too. Junior solves mate in 2 but fails to see mate in 3. So rybka is not alone.

Deep Junior 10.1
39.01   0:01   -0.75   1...Kf2 (1.365.972)
42.01   0:02   -1.05   1...Kf2 (3.183.917)
45.01   0:03   -1.35   1...Kf2 (5.609.593)
47.01   0:05   -1.65   1...Kf2 (8.752.368)
49.01   0:08   -1.95   1...Kf2 (14.563.601)
51.01   0:13   -2.25   1...Kf2 (24.866.697)
53.01   0:22   -2.55   1...Kf2 (43.897.511)
best move: Ke2-f2 time: 0:26.766 minnodes: 44.023.593

Deep Junior 11.2
33.01   0:01    0.00   1...Ba7 2.Kh2 Bf2 3.Kh1 (2.856.786) 1510
36.01   0:02    0.00   1...Ba7 2.Kh2 Bf2 3.Kh1 (3.721.269) 1400
38.01   0:03    0.00   1...Ba7 2.Kh2 Bf2 3.Kh1 (4.593.678) 1324
40.01   0:04    0.00   1...Ba7 2.Kh2 Bf2 3.Kh1 (5.272.672) 1227
42.01   1:55    0.00   1...Ba7 2.Kh2 Bf2 3.Kh1 (139.333.871) 1201
best move: Bg1-a7 time: 1:58.891 min  n/s: 1.301.962
Parent - By Lukas Cimiotti (Bronze) [de] Date 2010-06-06 16:05
Looks like a zugzwang/nullmove problem.
Parent - By Master Om (Bronze) [in] Date 2011-09-15 02:00
So Junior is also Rybka clone :-)
Up Topic Rybka Support & Discussion / Rybka Discussion / Rybka misses simple mate in 2

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