Endgame bug in Isa

Daniel Anulliero · Post by **Daniel Anulliero** » Thu Dec 15, 2016 7:19 pm

An interresting bug ocurred in a game Gogobello 0.12 - Isa :

[pgn]
[Site "GrahamCCRL.dyndns.org\Isa Gauntlet.ele"]
[Date "12-12-2016"]
[White "Gogobello 0.12 64-bit "]
[Black "Isa 1.9.51 64-bit "]
[Result "1/2-1/2"]
[TimeControl "4032:000 "]

1. Nf3 Nf6 2. c4 c6 3. g3 d5 4. Bg2 Bf5 5. cxd5 cxd5 6. Qb3 Qb6 7. Nc3
Qxb3 8. axb3 Nc6 9. d3 e5 10. Bg5 Be6 11. Nd2 O-O-O 12. Bxf6 gxf6
13. e4 d4 14. Nd5 f5 15. f4 fxe4 16. dxe4 exf4 17. Nxf4 Kb8 18. Bh3
Bxh3 19. Nxh3 Rd7 20. Rf1 Bb4 21. O-O-O Re7 22. Nf3 Rxe4 23. Nhg5
Rg4 24. Nxf7 Re8 25. N7g5 Re7 26. Nh3 Rd7 27. Nf2 Rg8 28. Nd3 Bd6
29. Nd2 Re7 30. Nc4 Bc7 31. Rf6 Rc8 32. Kb1 Rce8 33. Ka2 Re2 34. Rh6
R8e7 35. Rf1 Nd8 36. Rf8 b6 37. Rh8 Rd7 38. R6xh7 Rxh7 39. Rxh7 Nc6
40. Rh6 Kb7 41. Ka3 a6 42. Rh7 Kb8 43. g4 Rg2 44. h3 Rg1 45. Ka2 Rd1
46. Rh6 Kb7 47. Nxb6 Bxb6 48. Rh7 Kb8 49. Rh6 Rxd3 50. Rxc6 Kb7 51. Rh6
Rg3 52. Rh7 Kc6 53. Rh6 Kb5 54. b4 d3 55. Rd6 Rxh3 56. g5 Rg3 57. g6
Bf2 58. Kb3 Be1 59. Rf6 Rg5 60. Rd6 Bxb4 61. Rxd3 a5 62. Rd8 a4 63. Ka2
Rxg6 64. Rb8 Rb6 65. Rh8 Bc5 66. Rh5 Rf6 67. Rh2 Rf4 68. Rd2 Kb4
69. Ka1 Rf2 70. Rd7 Kb3 71. Rd3 Kc4 72. Rc3 Kb5 73. Rd3 Be7 74. Rd7
Bf6 75. Ka2 Bxb2 76. Rb7 Kc5 77. Rxb2
1/2-1/2
[/pgn]

Here is the position after 75.Ka2 :
[d]8/3R4/5b2/1k6/p7/8/KP3r2/8 b - - 23 75

isa played Bxb2 at depth 11 , witch was a draw .Taking the pawn with the rook was a win

Code: Select all

1 580 0        29   f6b2
2 590 0       115   f2b2 a2a3 b2b3 a3a2
3 608 0       232   f2b2 a2a3 b2b3 a3a2 b5c5
4 583 0      1718   f2b2 a2a3 b2b3 a3a2 b5c5 d7a7

5 580 0      5672   f2b2 a2a3 b2b3 a3a2 b5c5 d7a7 b3b4

6 576 0     19241   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5c5 b7a7 c5b5
7 580 0     37446   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5a5 b7a7 a5b4 a7b7 b4c4 b7a7
8 576 0     79858   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5a5 b7a7 a5b4 a7b7 b4c4 b7a7 c4b5
9 575 1    438181   f2b2 a2a3 b2b3 a3a2 b3g3 d7b7 b5c5 b7a7 c5b4 a7b7 b4c4 b7a7 c4b5
10 569 2    954966   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5c5 b7a7 c5b4

11 588 9   3821457   f6b2 d7b7 b5c5 b7c7 c5d5 c7c8 b2e5 a2a3 f2f4 c8a8 e5d6 a3b2 a4a3 a8a3 d6a3 b2a3 d5e5

Then I got an idea to fix this kind of blunder . I implemented the a/h passer rule :
-if position KPK and
-if the passer is on a or h file and
-if the ennemy king can reach or control the promotion square then
It's a draw

Now Isa play the correct move and it reach even a depth more :

Code: Select all

1 580 0        29   f6b2

2 590 0       130   f2b2 a2a3 b2b3 a3a2
3 608 0       234   f2b2 a2a3 b2b3 a3a2 b5c5

4 583 0      1597   f2b2 a2a3 b2b3 a3a2 b5c5 d7a7
5 580 0      5181   f2b2 a2a3 b2b3 a3a2 b5c5 d7a7 b3b4
6 576 0     16094   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5c4 b7a7 c4b5

7 582 0     38668   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5a5 b7a7 a5b4 a7b7 b4c5 b7a7
8 576 0    131447   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5a5 b7a7 a5b4 a7b7 b4c5 b7a7 c5b5
9 573 1    301219   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5a5 b7a7 a5b4 a7b7 b4c4 b7c7 c4d5 c7d7 d5c6 d7a7
10 569 2    741668   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5a5 b7a7 a5b4 a7b7 b4c4 b7c7 c4d5 c7a7 e3e4 a7a5 d5d6
11 577 5   1494719   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5c5 b7c7 c5b6 c7c4 b6b5 c4f4 f6e5 f4g4 a4a3
12 584 12   3809855   f2b2 a2a3 b2b3 a3a2 b3e3 d7b7 b5a6 b7c7 f6e5 c7d7 a6b5 d7b7 b5a5 b7a7 a5b4 a7b7 b4c5 b7a7

Of course it can't find the correct move at Depth one because I haven't the checks in Qs yet

And to finish my post , I would say thank you very much to Graham Banks for his Isa's broadcast (port 16063) .It's very interresting to see the games in live and at low TC (40/40) , you have the time to notice "some" bugs (30-40 per games )

bests
Dany