Maybe not a very interesting move, it may not even be a winning move if Black defends well, but apparently it can cause some difficulties in QSearches, at least the last builds of Toga that I made totally exploded their searches for some reason. Either that or it must be a bug somewhere in the search possibly introduced by my own spaghetti-code The hashfill-rate goes to zero but the NPS does not stop, search goes on so I think it must be the quiescence search because that does not use the hashtables.

[Event "12 Minutes/Game + 6 Seconds/Move"]

[Site "Engine Match"]

[Date "2008.04.07"]

[Round "2"]

[White "Naum 3"]

[Black "Shredder 11+ Beta6c"]

[Result "1-0"]

1. e4 {book 0s} e5 {book 0s} 2. Nf3 {book 0s} Nc6 {book 0s}

3. Bb5 {book 0s} a6 {book 0s} 4. Bxc6 {book 0s} dxc6 {book

0s} 5. O-O {book 0s} Qd6 {book 0s} 6. Na3 {book 0s} Be6

{book 0s} 7. Qe2 {book 0s} f6 {book 0s} 8. Rd1 {book 0s}

O-O-O {book 0s} 9. Nc4 {book 0s} Qe7 {book 0s} 10. d3 {book

0s} h5 {-0.10/14 33s} 11. b3 {+0.31/13 29s} Qe8 {-0.19/14

35s} 12. Be3 {+0.27/13 32s (Bb2)} h4 {-0.21/14 29s} 13. d4

{+0.28/13 20s (h3)} h3 {+0.30/14 35s} 14. dxe5 {+0.15/13

19s} Rxd1+ {+0.28/14 33s} 15. Rxd1 {+0.04/14 28s} hxg2

{+0.29/15 38s} 16. Bf4 {0.00/14 45s} Bg4 {?}{-0.86/14 3:39m}

{[D]2k1qbnr/1pp3p1/p1p2p2/4P3/2N1PBb1/1P3N2/P1P1QPpP/3R2K1 w - - bm Qe3;

In this testgame Naum 3 - Shredder 11 the Shredder settings I was testing produced a bad move 16... Bg4 {?!?} the move unfortunately is not reproducible in Analysis mode, at least, I have to be more precise: Bg4 is seen to be a bad move, in Analysis mode earlier, in the game Shredder sees it is -0.86 at depth 14 but maybe there is not time anymore to find a better move after thinking 3 minutes 39 seconds? For 17... c5 {?!} Shredder also takes more than three minutes and that probably is much worse than exchanging on f3. Anyway, it may just be a problem with these settings. Naum 3 does well in finding 17.Qe3 {!}, in analysismode, with more hash, Naum takes longer than the 33 seconds it needed in the game.}

17. Qe3 {!} {Not sure if it is enough for a full point if Black plays 17... Bxf3}{+0.78/12 33s} c5 {Probably the decisive mistake}{-1.92/14 3:47m} 18. exf6 {+1.79/13 1:01m} Rh3 {-1.92/14 14s} 19. Bg3 {+1.74/14 17s} gxf6 {-1.97/13 17s} 20. Qf4 {+2.52/16 41s} Rxg3 {-2.24/14 25s} 21. fxg3 {+2.52/16 19s (Qxg3)} Bd7 {-2.21/13 20s}

22. e5 {+2.62/15 31s} Bh6 {-2.32/13 8s} 23. Qe4 {+2.70/15

22s} f5 {-2.26/14 12s} 24. Qh4 {+2.69/14 34s (Qd5)} b5

{-2.27/14 9s} 25. Na5 {+2.69/15 14s (e6)} Qg6 {-2.63/14 9s}

26. Kxg2 {+2.56/15 19s} f4 {-2.83/14 22s} 27. Rd3 {+2.57/15

23s} fxg3 {-2.83/14 1:06m} 28. hxg3 {+2.57/15 9s} Bg7

{-2.72/12 4s} 29. a3 {+2.57/15 37s (a4)} Nh6 {-2.58/12 5s}

30. Qe7 {+4.03/16 13s} Qxg3+ {-2.93/13 4s} 31. Kh1

{+4.12/18 17s (Kxg3)} Qg4 {-2.71/12 4s} 32. e6 {+4.12/18

25s} Qh3+ {-3.45/14 14s} 33. Nh2 {+4.12/19 20s} Qxe6

{-3.45/15 4s} 34. Qxg7 {+4.17/18 23s} Nf5 {-3.45/14 6s}

35. Qf8+ {+4.81/13 10s (Qh8+)} Be8 {-3.17/13 8s} 36. Qxc5

{+4.81/15 10s} Bg6 {-3.17/12 3s} 37. Qf8+ {+4.81/16 33s}

Be8 {-3.26/12 5s} 38. Nf1 {+4.81/17 13s (Kg1)} Qg6

{-3.67/12 7s} 39. b4 {+4.81/17 24s (c4)} Qe6 {-3.60/12 6s}

40. Kg1 {+5.10/15 8s} Qg6+ {-4.45/13 8s} 41. Kf2 {+5.12/16

13s} Nd6 {-4.21/13 6s} 42. Ng3 {+5.12/16 9s (Ne3)} Kb8

{-4.53/13 5s} 43. Nf5 {+5.42/15 11s} Qxf5+ {-5.12/14 5s}

44. Qxf5 {+5.12/4 0s} Nxf5 {-4.71/16 0s} 45. Rd8+ {+6.24/16

9s} Ka7 {-4.71/10 0s} 46. Rxe8 {+6.24/18 54s} Nd6 {-4.99/17

3s} 47. Rf8 {+7.10/17 43s (Re7)} c6 {-6.83/16 15s}

48. Nxc6+ {+7.17/16 38s (Rd8)} Kb7 {-8.58/18 7s} 49. Na5+

{+7.17/15 14s (Ne5)} Kc7 {-10.72/19 7s} 50. Ke3 {+7.17/15

13s} Kd7 {-10.72/18 6s} 51. Ra8 {+7.90/15 12s} Nf5+

{-10.89/16 6s} 52. Kd3 {+8.10/15 6s} Nh4 {-11.14/15 6s}

53. Rxa6 {+8.10/14 10s} Nf3 {-11.84/16 6s} 54. Rb6

{+8.10/14 9s} Ne5+ {-12.04/16 5s} 55. Kc3 {+8.10/14 5s

(Kd4)} Kc7 {-12.83/16 14s} 56. Rxb5 {+8.10/14 6s} Ng6

{-12.83/15 0s} 57. Rb7+ {+10.22/14 12s} Kc8 {-14.10/16 2s}

58. b5 {+14.91/15 6s (a4)} Nf4 {-279.83/18 6s} 59. Kc4

{+M29/14 2s (b6)} Ng6 {-M7/20 5s} 60. Rg7 {+M24/10 0s (b6)}

Kd8 {-M8/17 10s} 61. Rxg6 {+M9/9 0s (Nc6+)} Ke7 {-M7/16 3s}

62. b6 {+M8/7 0s (Nc6+)} Kf7 {-M5/15 3s} 63. Rg1 {+M7/5 0s

(Rc6)} Kf6 {-M5/15 6s} 64. b7 {+M6/2 0s} Ke5 {-M4/13 2s}

65. b8=Q+ {+M5/2 0s} Ke6 {-M3/12 4s} 66. Qe8+ {+M4/1 0s

(Nc6)} Kf5 {-M2/12 3s} 67. Kd5 {+M2/1 0s} Kf4 {-M1/11 1s}

68. Qe4# {+M1/1 0s} 1-0

Build 70 of Toga here only gets as far as 9 ply, does see Qe3 but can't resolve it:

Build 70: tries to reign in extensions in QSearch but is not successful enough, extensions only allowed if depth > -1 instead of depth > 0, still QSearch explodes on ply 9, does find Ne3 at this depth what Build 69 does not. Changes in search_full.cpp:

// extensions

if (MOVE_IS_PROMOTE(move) && depth > -20 && depth <

**-1**) {

ASSERT(PIECE_IS_PAWN(piece));

depth++; // pawn promotion extension

}

else if (single_reply && depth > -30 && depth <

**-1**) {

depth++; // single reply extension

}

2k1qbnr/1pp3p1/p1p2p2/4P3/2N1PBb1/1P3N2/P1P1QPpP/3R2K1 w - -

Engine: Toga 1.5 Checkov_beta1 bb5men test4 (256 MB, Athlon 2009 MHz, Build 70, d.d. 8-04-2008 2:42 CET, "test 4" just refers to the used settings, no bitbases working as yet although switched on in settings)

by Letouzey, Gaksch, Pudas and de Groot

1/14 0:00 +0.79 17.exf6 Nxf6 (102)

1/14 0:00 +0.99 17.Kxg2 Kb8 18.exf6 Nxf6 (393)

2/16 0:00 +0.98 17.Kxg2 Kb8 18.exf6 Nxf6 (4.342)

3/16 0:00 +0.48 17.Kxg2 Kb8 18.Kg1 Bc5 19.exf6 Nxf6 (6.972)

3/16 0:00 +0.54 17.exf6 Nxf6 18.Be5 Kb8 19.Bxf6 gxf6

20.Kxg2 (7.625)

4/16 0:00 +0.20 17.exf6 Nxf6 18.Nce5 Bc5 19.Nxg4 Nxg4

20.Kxg2 Nxf2 (10.839)

4/17 0:00 +0.25 17.Kxg2 g5 18.Be3 Rh3 19.Ncd2 fxe5

20.Bxg5 (19.212)

5/24 0:00 +0.25 17.Kxg2 g5 18.Be3 Rh3 19.Ncd2 fxe5

20.Bxg5 (55.738)

6/24 0:00 +0.25 17.Kxg2 g5 18.Bg3 Kb8 19.Ne3 Bh3+

20.Kh1 Bc5 21.exf6 Qxe4 22.Rd8+ Bc8 (82.471)

7/26 0:00 +0.19 17.Kxg2 g5 18.Bg3 Kb8 19.Ne3 Bh3+

20.Kh1 g4 21.Nh4 (221.305)

8/31 0:01 0.00 17.Kxg2 g5 18.Bg3 Bc5 19.a4 Kb8

20.Kh1 Qf8 21.Ne3 (565.906) 423

8/31 0:01 +0.41 17.Ne3 Be6 18.Nxg2 g5 19.Bg3 g4

20.Nd4 Bc5 21.Nxe6 Qxe6 (785.772) 423

9/31 0:02 +0.38 17.Ne3 Be6 18.Nxg2 g5 19.Bg3 Bc5

20.Nd4 Bxd4 21.Rxd4 Kb8 22.Ne3 (878.818) 411

best move: Nc4-e3 time:

**7:39.750 min**n/s: 566.572 CPU 100.0% n/s(1CPU): 566.572 nodes: 260.340.000

Build 71 was a bit more succesful I'm happy to say But in Blitzgames I don't think very many engines will find 17.Qe3 I have not tried it yet though, maybe it's an easy move.

Eelco