bdmendes / camel

Bitboard-based UCI-compatible chess/chess960 engine written from scratch in Rust.

About me

• 👨‍💼 Software Engineer @ Kevel
• 📖 FEUP Alumni
• 🎲 Club chess player

camel's Issues

Rewrite the engine to allow for incrementally updated NNUE (v2.x)

Make it simpler and more optimized from the ground up.

Add LazySMP gauntlet testing to CI

Investigate and train NNUE to replace hand-crafted evaluation

Camel v1.2.0 outperforms v1.3.0 in puzzle

Lately i gave this position to several engines. Camel v1.2.0 finds the solution Rd1 at depth 9 after 2 seconds, but v1.3.0 finds it only at depth 28 after 100 seconds !?

White to move.

7Q/p2r4/kp6/4Bp2/P3b3/KP1q4/8/2R5 w - - 0 1

Speedup eval with SIMD instructions

Endgame tablebases

E.g. Syzygy.

Multi-threaded search

E.g using LazySMP.

Better pawn structure evaluation

Currently, only considers isolated and doubled pawns. Should also consider connectivity, blocked and passed pawns.

Tweak tapered psqt values

King safety evaluation

E.g king tropism and pawn chains.

Ponder in opponent's time

Cleanup nearby entries when probing from hash table

The table is filling up too fast; cleanup (old?) entries nearby when probing.

Support Chess960

Improve LazySMP variability

Opening book

hi, i just discovered your engine by the Public download list at https://drive.google.com/drive/folders/1vmtiWtIZoBDqkarEm1_rLT9_l0eq0qr3 .. i managed to compile v0.3.1 on Xubuntu 22.04 and it runs fine in CuteChess (GUI) !

however, Camel does not seem to know how to play the opening : it likes to develop the Queens kNight to c3 / c6 very early in the opening, it often just starts with that move, and this is a difficult setup : it's playable, but the move blocks the c-pawn and the kNight can easily be kicked to other squares, none of which are safe .. the kNight might be captured .. if not, Camel will get a bad position where all pieces are disharmonious ..

this might sound harsh, but i'm a chess player myself .. and i gather and test many chess engines (only on Linux) also weaker ones, and i know many such engines have the same habbit : their pawn-piece setup is bad, the Queens kNight should not be developed that way .. normally .. it CAN be played (SF knows how), it's a known opening, but rare and you must know how to put the (other) pieces ..

here's a game of Camel playing Black :

i'm a programmer, but not yet of any engine .. i don't know how you can improve Camel with my information .. but maybe when NOT playing Nc3 / Nc6 early, Camel can play a decent game ?

Improve check handling in movegen

E.g. by using check evasions.

handle negative time

while playing a game with Camel v1.5.0 (compiled on Xubuntu 22.04) it received an "invalid command" and lost .. this was due to negative remaining time of the opponent, being a human : CuteChess allows negative time for humans. You probably didn't know this fact about CuteChess .. i guess you can easily adjust the concerning code part to anticipate this "behaviour".
NOTE: whenever an engine runs out of time, CuteChess ends the game after 15 seconds.

here's the CuteChess log tail :

[...]
<Camel v1.5.0(0): info depth 12 score cp 143 time 973 nodes 833005 nps 856035 hashfull 492 pv d5b3 g8f6 f1e1 e7e6 d1d3 e8g8 c1e3 b8d7 b1c3 c8b7 e4e5 d6e5
<Camel v1.5.0(0): info depth 13 score cp 143 time 1446 nodes 1278642 nps 883673 hashfull 508 pv d5b3 g8f6 f1e1 e7e6 d1d3 e8g8 c1e3 b8d7 b1c3 c8b7 e4e5 d6e5 d4e5
<Camel v1.5.0(0): bestmove d5b3 ponder g8f6
>Camel v1.5.0(0): position startpos moves g1f3 g7g6 d2d4 f8g7 e2e4 d7d6 f1c4 a7a6 e1g1 b7b5 c4d5 c7c6 d5b3 c8b7
>Camel v1.5.0(0): isready
<Camel v1.5.0(0): readyok
>Camel v1.5.0(0): go wtime 165661 btime -170671 winc 2000 binc 2000
<Camel v1.5.0(0): Invalid command. Type 'help' to know more.
>Camel v1.5.0(0): stop

Make piece values depend on the board

E.g. a bishop is bad if friendly pawns are of the same colour; two connected rooks are more valuable.

Late move reductions

Camel v1.1.0 can not mate

i just let Camel v1.1.0 (compiled on Xubuntu 22.04) play a game in CuteChess .. the engine was clearly winning but it could not mate ..

in this position Camel (Black) promoted to a Queen, but the game ended in a draw by repetition :

---

[Event "engine vs engine"]
[Site "Holland"]
[Date "2023.09.12"]
[Round "?"]
[White "Tofiks v1.1.0"]
[Black "Camel v1.1.0"]
[Result "1/2-1/2"]
[FEN "rnbqkbnr/pppp1ppp/8/4p3/8/3P2P1/PPP1PP1P/RNBQKBNR b KQkq - 0 2"]
[GameDuration "00:21:57"]
[PlyCount "208"]
[SetUp "1"]
[TimeControl "180+10"]

1... d5 {+0.73/9 8.5s} 2. Bg2 {-0.37/9 13s} Nf6 {+0.77/9 11s}
3. Nf3 {-0.23/9 13s} Nc6 {+0.84/9 9.3s} 4. O-O {-0.04/9 13s} Bf5 {+0.71/9 13s}
5. e3 {-0.14/8 13s} Bd6 {+0.64/8 13s} 6. Nc3 {-0.08/9 13s} Bb4 {+0.57/8 10s}
7. a3 {-0.04/8 13s} Bxc3 {+0.73/10 14s} 8. bxc3 {+0.15/10 13s} O-O {+0.69/8 14s}
9. Bb2 {+0.40/9 13s} Re8 {+0.80/9 14s} 10. h3 {+0.57/10 13s} Qd6 {+0.77/9 11s}
11. Nd2 {+0.46/9 13s} e4 {+0.80/8 14s} 12. c4 {+0.92/9 13s} exd3 {+0.38/9 15s}
13. cxd5 {+1.17/9 13s} Ne5 {-0.04/9 15s} 14. c4 {+1.33/8 14s} Qa6 {+0.26/8 12s}
15. Bd4 {+1.44/8 14s} Re7 {+0.14/8 14s} 16. f4 {+1.58/8 14s} Nxc4 {+0.43/10 17s}
17. Nxc4 {-0.05/10 14s} Qxc4 {+0.44/10 17s} 18. Rb1 {-0.05/9 14s}
Rd8 {+0.57/8 17s} 19. g4 {+0.62/9 14s} Bc8 {+0.05/9 17s} 20. Qb3 {+0.34/9 14s}
Qxb3 {+0.31/10 11s} 21. Rxb3 {+0.10/11 14s} b6 {+0.27/10 17s}
22. Bxf6 {+0.24/11 14s} gxf6 {+0.17/11 16s} 23. e4 {+0.04/11 14s}
Ba6 {+0.24/11 16s} 24. Rd1 {+0.19/11 15s} Bc4 {+0.22/12 13s}
25. Rc3 {+0.19/12 15s} b5 {+0.23/12 15s} 26. a4 {-0.06/12 15s} a6 {+0.23/12 14s}
27. axb5 {0.00/12 15s} axb5 {+0.24/11 9.8s} 28. Bf3 {-0.10/12 15s}
Ra8 {+0.28/10 14s} 29. f5 {-0.05/11 15s} Ree8 {+0.34/11 14s}
30. Kf2 {-0.02/12 15s} Ra4 {+0.25/10 13s} 31. h4 {+0.04/11 14s}
Kf8 {+0.23/9 14s} 32. Rd2 {+0.08/12 14s} h6 {+0.23/10 14s}
33. Rc1 {+0.05/12 14s} Ke7 {+0.31/11 14s} 34. Rf1 {+0.12/11 13s}
b4 {+0.49/12 13s} 35. Rc1 {+0.16/11 13s} b3 {+0.53/11 11s}
36. Kg3 {+0.09/11 13s} Kd6 {+0.72/10 12s} 37. Rg2 {+0.19/10 12s}
Rb8 {+0.86/11 15s} 38. Rb1 {-0.05/11 12s} Ra2 {+0.93/11 13s}
39. Rbb2 {-0.14/11 12s} Ke5 {+1.18/12 15s} 40. h5 {-0.83/13 12s}
Kd4 {+3.67/12 12s} 41. d6 {-1.33/13 12s} cxd6 {+4.83/12 14s}
42. g5 {-4.15/12 12s} fxg5 {+5.91/11 7.2s} 43. e5 {-6.58/13 11s}
dxe5 {+8.50/11 9.3s} 44. f6 {-8.72/12 11s} Kc3 {+8.50/11 14s}
45. Rb1 {-9.28/13 11s} Rxg2+ {+9.44/12 14s} 46. Bxg2 {-9.78/12 11s}
b2 {+11.15/13 14s} 47. Be4 {-12.38/16 11s} Ba2 {+11.36/13 13s}
48. Rxb2 {-12.94/15 11s} Rxb2 {+14.89/13 8.4s} 49. Bf3 {-15.09/16 11s}
Re2 {+16.09/13 13s} 50. Bg4 {-23.35/17 11s} Bc4 {+M13/13 10s}
51. Bd7 {-23.35/16 11s} d2 {+M9/9 0.19s} 52. Kh3 {0.00/15 11s}
d1=Q {+M1/1 0.013s} 53. Bc6 {-M4/3 0.003s} Qd3+ {+M1/1 0.012s}
54. Bf3 {-M4/1 0s} Qd1 {+M1/1 0.010s} 55. Bg2 {-M26/5 0.015s} Qa1 {+M1/1 0.012s}
56. Kg3 {-M6/5 0.011s} Rxg2+ {+M1/1 0.012s} 57. Kxg2 {-M26/3 0.001s}
Qb2+ {+M1/1 0.013s} 58. Kg3 {-M6/5 0.017s} Qc2 {+M1/1 0.013s}
59. Kg4 {-M6/5 0.009s} Qe4+ {+M1/1 0.012s} 60. Kg3 {-M10/1 0s}
Qh4+ {+M1/1 0.012s} 61. Kg2 {-M22/5 0.020s} Be2 {+M1/1 0.012s}
62. Kg1 {-M4/3 0s} Bf3 {+M1/1 0.013s} 63. Kf1 {-M6/5 0.006s} Kd2 {+M1/1 0.014s}
64. Kg1 {-M4/3 0s} Kc2 {+M1/1 0.013s} 65. Kf1 {-M6/3 0.001s} Bg4 {+M3/3 0.036s}
66. Kg2 {-M8/6 0.014s} Kc3 {+M1/1 0.012s} 67. Kf1 {-M10/3 0.001s}
Bd1 {+M1/1 0.013s} 68. Kg1 {-M8/3 0.001s} Be2 {+M1/2 0.025s} 69. Kg2 {-M12/3 0s}
Qd4 {+M1/1 0.012s} 70. Kh3 {-M14/3 0.001s} Qh4+ {+M1/1 0.012s}
71. Kg2 {-M12/1 0s} Qg4+ {+M1/2 0.026s} 72. Kh2 {-M12/4 0.009s}
Qf3 {+M1/1 0.012s} 73. Kg1 {-M8/2 0s} Bc4 {+M1/1 0.013s} 74. Kh2 {-M18/2 0s}
Qe4 {+M1/1 0.013s} 75. Kg1 {-M20/3 0.001s} Qe3+ {+M1/1 0.013s}
76. Kg2 {-M22/3 0.002s} Qe1 {+M1/1 0.012s} 77. Kf3 {-M30/3 0.001s}
Qe2+ {+M1/1 0.012s} 78. Kg3 {-M8/2 0s} Kd2 {+M1/1 0.012s} 79. Kh3 {-M14/2 0s}
Kc3 {+M1/1 0.012s} 80. Kg3 {-M8/2 0s} Qd3+ {+M1/1 0.012s}
81. Kf2 {-M26/2 0.001s} Qc2+ {+M1/1 0.013s} 82. Kg1 {-M26/2 0s}
Qe4 {+M1/1 0.011s} 83. Kf2 {-M24/2 0s} Qh4+ {+M1/1 0.012s} 84. Kg2 {-M22/2 0s}
Qd4 {+M1/1 0.013s} 85. Kh3 {-M26/3 0.001s} Qd3+ {+M1/1 0.012s}
86. Kg2 {-M24/2 0s} Qc2+ {+M1/2 0.032s} 87. Kg1 {-M26/1 0s} Qd2 {+M1/1 0.013s}
88. Kh1 {-M24/3 0s} Qe1+ {+M1/1 0.016s} 89. Kg2 {-M20/2 0s} Kd2 {+M1/1 0.013s}
90. Kh3 {-M12/4 0.004s} Qf2 {+M1/1 0.012s} 91. Kg4 {-M2/2 0s}
Be2+ {+M1/1 0.012s} 92. Kh3 {-M2/1 0s} Qh4+ {+M1/1 0.012s}
93. Kg2 {-M6/2 0.001s} Kc3 {+M3/3 0.036s} 94. Kg1 {-M8/2 0s} Bb5 {+M1/1 0.012s}
95. Kg2 {-M18/6 0.017s} Bc4 {+M1/2 0.022s} 96. Kf3 {-M18/2 0s}
Kd2 {+M1/1 0.012s} 97. Kg2 {-M14/3 0s} Kc3 {+M3/3 0.035s} 98. Kf3 {-M18/2 0s}
Qe1 {+M1/1 0.012s} 99. Kg2 {-M22/2 0s} Qe4+ {+M1/1 0.012s} 100. Kh3 {-M30/1 0s}
Qc2 {+M1/1 0.012s} 101. Kg3 {-M28/2 0s} Be6 {+M1/1 0.012s}
102. Kf3 {-M6/4 0.002s} Bc4 {+M1/1 0.014s} 103. Kg3 {-M30/2 0s}
Qe2 {+M1/1 0.013s} 104. Kh3 {-M6/2 0s} Qe1 {+M1/1 0.012s}
105. Kg2 {0.00/50 0.001s, Draw by 3-fold repetition} 1/2-1/2