Rybka 3 cannot find an obvious draw

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Topic Rybka Support & Discussion / Rybka Discussion / Rybka 3 cannot find an obvious draw

By domelius Date 2010-02-16 02:54 Edited 2010-02-16 03:51

Hi people,

a few words about me first: I am a weak player from Bulgaria, my current national rating is 2120, I dont have international Elo (must be similar if I had one).
I played a Blitz game against Rybka 3 at full strenght, without using any help and without taking back any moves. Rybka had 1 min for the whole game, I had a human Bonus of 1 hour. I was very happy to achieve a draw thanks to a weakness into the position valuation of the engine. Here I paste the game moves:

[Event "Blitz:1'"]
[Site "?"]
[Date "2010.02.16"]
[Round "?"]
[White "Rybka 3 1-cpu 32-bit"]
[Black "Dimov, Dimcho"]
[Result "1/2-1/2"]
[ECO "B22"]
[Annotator ",Dimcho"]
[PlyCount "100"]
[EventDate "2010.??.??"]
[TimeControl "60"]

{24MB, Fritz11.ctg, DIMOV} 1. e4 c5 2. c3 d5 3. exd5 Qxd5
4. d4 Nf6 5. Nf3 g6 6. Qb3 Qxb3 7. axb3 cxd4 8. Nxd4 Bg7 9. Nb5 Na6 10. Rxa6 bxa6 11. Nc7+
Kd7 12. Nxa8 Bb7 13. f3 Rxa8 14. Na3 e6 15. Nc4 Nd5 16. Na5 Bc8 17. b4 Rb8 18. Bd3 Nc7 19.
Be3 Nb5 20. Kf2 Bb7 21. Nxb7 Rxb7 22. Ra1 Nxc3 23. bxc3 Bxc3 24. Rxa6 Bxb4 25. g3 f6 26. Bc4
Bd6 27. Rxa7 Rxa7 28. Bxa7 e5 29. Bd5 f5 30. Be3 f4 31. gxf4 exf4 32. Bd4 g5 33. Ke2 h5 34. Bf7
g4 35. Bxh5 gxf3+ 36. Kxf3 Ke7 37. h4 Ke6 38. Ke4 Be7 39. Bg4+ Kf7 40. h5 Bf6 41. Bxf6 Kxf6
42. Kxf4 Kg7 43. Kg5 Kh8 44. Kg6 Kg8 45. h6 Kh8 46. Bf5 Kg8 47. Bb1 Kh8 48. Bd3 Kg8 49. Be4 Kh8
50. Bb1 Kg8 1/2-1/2

This position is a dead draw, and the program still gives a +6.00 for white. The draw is achieved after 41. Bxf6, which is a blunder. The program should also avoid to exchange the f and g pawns. Fritz 11 on the other hand refuses correctly to exchange the bishops in this position and after 41. Bxf6 sees the draw immediately.

And here a similar position:

Black to move and draw:

Rybka cannot find the line 1...Ra1+ 2. Rf1 Rxf1+ 3. Kxf1 Bh3!!. The move 3... Bh3!! is the only move which saves the game for back, and is easily found by Fritz 11 and Shredder 12, but not by Rybka.

I am writing this statement not to boast about my draw with Rybka, I just want to give you a tip for improvement for the next versions, if you havent already noticed this weakness.

Best regards,

D.Dimov

By vdragan (***)

Date 2010-02-16 03:50

noticed loooong time ago :)

By Gaмßito (****)

Date 2010-02-16 03:52 Edited 2010-02-16 04:04

Yes, this is already a very known topic.

The wrong bishop knowledge was removed after Rybka 2.1. Then, Vas promised to return this knowledge again for Rybka 3 but he forgot it. And many months ago, he told us that this problem was already fixed, so there will be no problems with Rybka 4 for these positions. (If Rybka 4 is released. But I doubt it, ever more and more. :-)).

r7/8/8/5bk1/8/5B2/5RPP/6K1 b - - 0 1

Analysis by Rybka 1.2n 32-bit:

1...Ra1+ 2.Rf1 Ra3 3.g3 Bh3
+/- (1.05)   Depth: 6   00:00:00 15kN
1...Ra1+ 2.Rf1 Ra4 3.g3 Bh3 4.Re1
+/- (1.05)   Depth: 7   00:00:00 34kN
1...Ra1+ 2.Rf1 Ra4 3.g3 Bh3 4.Re1 Kf6
+/- (1.10)   Depth: 8   00:00:00 54kN
1...Ra1+ 2.Rf1 Ra3 3.Kf2 Rc3 4.Re1 Rc2+ 5.Re2 Rc4
+/- (1.15)   Depth: 9   00:00:01 104kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5
= (0.00)   Depth: 10   00:00:02 244kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7
= (0.00)   Depth: 11   00:00:02 303kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Ke3
= (0.00)   Depth: 12   00:00:03 414kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 13   00:00:04 663kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 14   00:00:05 1033kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 15   00:00:06 1452kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 16   00:00:08 2041kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 17   00:00:10 2872kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 18   00:00:13 3978kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 19   00:00:17 5374kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 20   00:00:23 7182kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 21   00:00:32 9649kN
1...Ra1+ 2.Rf1 Rxf1+ 3.Kxf1 Bh3 4.Kf2 Bxg2 5.Bxg2 Kf6 6.h4 Kg7 7.h5 Kh7 8.Be4+
= (0.09)   Depth: 22   00:00:42 12839kN

(AMD, 15.02.2010)

6k1/8/6KP/8/8/8/8/1B6 w - - 0 1

Analysis by Rybka 1.2n 32-bit:

1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6
= (0.09)   Depth: 6   00:00:00 11kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8
= (0.09)   Depth: 7   00:00:00 21kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7
= (0.09)   Depth: 8   00:00:00 37kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3
= (0.09)   Depth: 9   00:00:00 61kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8
= (0.09)   Depth: 10   00:00:00 96kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 11   00:00:00 143kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 12   00:00:00 207kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 13   00:00:01 286kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 14   00:00:01 396kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 15   00:00:01 538kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 16   00:00:02 711kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 17   00:00:02 903kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 18   00:00:03 1160kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 19   00:00:03 1458kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 20   00:00:04 1960kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 21   00:00:05 2251kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 22   00:00:05 2566kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 23   00:00:06 2905kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 24   00:00:06 3275kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 25   00:00:07 3718kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 26   00:00:08 4207kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 27   00:00:09 4771kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 28   00:00:10 5372kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 29   00:00:11 6006kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 30   00:00:12 6644kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 31   00:00:13 7495kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 32   00:00:14 8235kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 33   00:00:16 9017kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 34   00:00:17 9849kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 35   00:00:19 10743kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 36   00:00:20 11707kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 37   00:00:22 12740kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 38   00:00:24 13837kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 39   00:00:26 15036kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 40   00:00:28 16282kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 41   00:00:30 17608kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 42   00:00:32 19042kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 43   00:00:34 20551kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 44   00:00:37 22135kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 45   00:00:40 24051kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 46   00:00:42 25787kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 47   00:00:45 27884kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 48   00:00:48 29912kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 49   00:00:51 31977kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 50   00:00:54 34140kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 51   00:00:57 36554kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 52   00:01:00 39135kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 53   00:01:04 42170kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 54   00:01:09 46982kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 55   00:01:13 50495kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 56   00:01:18 55573kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 57   00:01:23 61709kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 58   00:01:31 70425kN
1.h7+ Kh8 2.Kg5 Kg7 3.h8Q+ Kxh8 4.Kf6 Kg8 5.Ba2+ Kh7 6.Bb3 Kh8 7.Bc4 Kh7
= (0.09)   Depth: 59   00:01:39 79706kN

(AMD, 15.02.2010)

Regards,
Gaмßito.

By yanquis1972 (****)

Date 2010-02-16 03:54

first of all, congratulations on the draw nevertheless. you did not know it but you exploited (fairly) a very well known & much complained about 'bug' - rybka doesn't understand wrong bishop endings. the reason for this is presumably because including the knowledge led to an overall decrease in engine elo. if rybka was in the public eye & embarrassments such as this were witnessed enough (imagine such a thing happening in a big man-machine match), i am sure the appropriate change would be made and we would suffer an engine that is 3090 instead of 3100 elo or whathaveyou. the inconvenience of having to wait a few extra seconds for rybka to resolve a certain position every once in awhile might easily be superseded by the more accurate analysis & play for some, but vas apparently feels or felt otherwise.

By Felix Kling (Gold)

Date 2010-02-16 09:35

http://www.rybkachess.com/download/3-4%20men%20tablebases.zip

why not installing tablebases?

By domelius Date 2010-02-16 04:00

Ok, Thanks. And success with the new versions!

By BigBen

Date 2010-02-16 09:18 Edited 2010-02-16 09:30

Hi,
My Rybka does not play 41.Bxf6? in fact no engine I tested did so I assume you had no TBases loaded .... Choices tend to be 41.Bf2 or 41.Bb6 and I think white will win

No other engine tested in fact played 41.Bxf6 with or without TBases loaded

Regards

By yanquis1972 (****)

Date 2010-02-16 13:36

most users don't automatically have tablebases installed, certainly not 5 men. any engine should be smart enough to avoid this without tablebases & not need to use them as a crutch.

By Mark

Date 2010-02-16 14:33

I would think most users would have the full set of 5-man egtbs installed. Nowadays, 7 GB is nothing...

By yanquis1972 (****)

Date 2010-02-16 14:48

most heavy users yes, but probably not most users. it's a pain to DL 7GB of data from odd sites & no one wants to spend money on something that's free. i think 5 man TBs are probably still relatively uncommon among the entire pool of people who use chess engines.

By Mark

Date 2010-02-16 15:18

Maybe. I just finished downloading the 6-man egtbs! 1.2TBs took quite awhile...

By domelius Date 2010-02-16 09:39 Edited 2010-02-16 09:46

Hi Big Ben,

Ok, I dont have any tablebases. A tablebase for 7 pieces endgame, how big is that?

And a move from the bases is not an engine move at all.

By Felix Kling (Gold)

Date 2010-02-16 10:21

you just need the 5 men for that particular ending, as the engine uses the tablebases during calculation. you need just the files kbppk, that are rather small (50MB together). all 3-4-5 men tablebases are 7.1 GB total.

see http://kirill-kryukov.com/chess/tablebases-online/

Topic Rybka Support & Discussion / Rybka Discussion / Rybka 3 cannot find an obvious draw