babak-ssh / kojiro

A simple UCI Chess Engine

Kojiro

An UCI-compatible Chess Engine written in C++

Description

Kojiro is a free, UCI chess engine written from scratch in C++,which i have developed for fun and to learn about chess programming, it uses well-known concepts used in chess programming for many decades and a lot of ideas are taken from chessprogramming wiki and talk chess forum and open-source engines.

Features

• Search:
  • AlphaBeta Pruning
  • Aspiration Window
  • Iterative Deepening
  • Null Move Pruning
  • Razoring
  • Late Move Reductions
  • Quiescence Search
  • Multi Threads(Lazy SMP)
• Move Ordering:
  • Hash Move
  • TT Move
  • MVV/LVA
  • Killer heuristic
  • History heuristic
• Evaluation:
  • Evaluation Tapering
  • Piece Square Tables
  • Pawn Structure
  • Piece Mobility
  • Open Files
• Other:
  • Zobrist Hashing
  • Transposition Table
  • logging
  • UCI

Usage

you can use UCI protocol by running the main file or use an UCI-compatible graphical user interface(GUI) (e.g. Arena, Sigma Chess) in order to be used comfortably.

also you can challenge it on Lichess! --> https://lichess.org/@/tha_kojiro

Compiling Kojiro

to compile the engine use:

cd src
make kojiro
./kojiro

Tests

to compile perft tests

cd src
make perft

usage:

./perft depth fen
./perft 5 rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

inspiring open-source chess-engines:

• BBC by Maksim Korzh
• Stockfish by Tord Romstad, Joona Kiiski, Gary Linscott, Marco Costalba
• Rustic by Marcel Vanthoor
• Vice by BlueFeverSoft

Kojiro is still under develop

there are many techniques and features that will be added:

• use more modern cpp features to enhance the performance
• better evalution
  • pawn (push, shield)
  • center control, castling
  • piece pair, blocked pieces
• more tests
• futility prunning (in alpha-beta and quiescence)
• time distribution model for time management of moves
• opening books
• Syzygy support
• NNUE
• internal iterative deepening
• better sorting
  • Counter
  • LastCaptureBonus
  • SEE
  • Checks priority
  • En-passant priority
• Xboard protocol
• windows support
• wiki

kojiro's Issues

promotion bug : illegal move

i compiled Kojiro on Linux (Xubuntu 22.04) and it runs fine in CuteChess (GUI) but sometimes it makes an illegal move concerning promotion .. here are two examples :

[Event "?"]
[Site "?"]
[Date "2024.04.14"]
[Round "?"]
[White "Kojiro v0.1"]
[Black "Kittycat"]
[Result "0-1"]
[FEN "rnbqkb1r/ppp2ppp/5n2/3pp3/8/3PP3/PPPNNPPP/R1BQKB1R b KQkq - 3 4"]
[PlyCount "121"]
[SetUp "1"]
[Termination "illegal move"]
[TimeControl "900+3"]

1... Nc6 {+0.60/7 75s} 2. Ng3 {-0.39/12 21s} Be6 {+0.70/7 69s}
3. Be2 {-0.20/12 21s} Bc5 {+0.65/7 64s} 4. O-O {+0.02/12 22s} Qd6 {+0.55/7 44s}
5. a3 {+0.30/11 22s} O-O {+0.60/7 42s} 6. b4 {+3.59/14 22s} Bb6 {-0.35/8 34s}
7. c4 {+5.67/14 22s} Nd7 {-0.30/7 37s} 8. c5 {+5.69/14 23s} Nxc5 {-0.50/8 35s}
9. bxc5 {+5.77/13 23s} Bxc5 {-0.50/7 33s} 10. Nb3 {+5.81/12 23s}
Bb6 {-0.50/7 32s} 11. d4 {+5.58/12 23s} e4 {-0.55/6 30s} 12. Qc2 {+6.01/12 23s}
Rad8 {-0.60/5 28s} 13. Nc5 {+6.05/12 23s} Bxc5 {-0.70/8 21s}
14. dxc5 {+6.11/13 23s} Qe7 {-0.75/8 22s} 15. Rb1 {+6.02/12 22s}
Rb8 {-0.75/7 24s} 16. Bb2 {+6.28/11 22s} Qg5 {-0.85/7 23s}
17. Rbd1 {+6.35/10 22s} Ne7 {-0.85/7 19s} 18. Qa4 {+6.65/10 22s}
a6 {-0.80/7 21s} 19. Qc2 {+6.17/11 22s} Rfe8 {-0.75/6 20s}
20. Nh5 {+6.22/11 21s} Red8 {-0.90/6 19s} 21. h4 {+7.36/13 21s}
Qg6 {-1.35/7 14s} 22. Bxg7 {+7.29/12 21s} Bh3 {-1.40/6 17s}
23. Nf4 {+7.22/14 21s} Qxg7 {-1.75/7 16s} 24. Nxh3 {+7.13/13 20s}
Qe5 {-1.75/6 16s} 25. h5 {+7.14/11 20s} Nf5 {-1.80/6 15s} 26. Qb3 {+7.05/12 20s}
d4 {-1.75/7 11s} 27. Bc4 {+7.38/13 19s} dxe3 {-1.90/7 14s}
28. Rxd8+ {+8.62/13 19s} Rxd8 {-2.20/7 13s} 29. fxe3 {+8.62/12 19s}
Rd2 {-3.10/7 9.4s} 30. Bxf7+ {+8.68/12 18s} Kg7 {-2.70/6 12s}
31. Nf4 {+9.01/13 18s} Rb2 {-2.75/7 12s} 32. h6+ {+9.71/13 18s}
Kf6 {-3.00/6 11s} 33. Qc4 {+9.88/14 17s} Kg5 {-3.25/6 11s}
34. Bg8 {+9.54/13 17s} Nxe3 {-3.00/7 10s} 35. Qc1 {+8.42/14 17s}
Qxf4 {-3.00/7 9.6s} 36. Rxf4 {+8.90/17 16s} Rxg2+ {-3.10/9 7.1s}
37. Kh1 {+9.40/17 16s} Kxf4 {-2.80/9 6.1s} 38. Qe1 {+9.40/15 16s}
Rxg8 {-2.25/8 8.8s} 39. Qf2+ {+10.67/15 15s} Ke5 {-2.25/8 8.5s}
40. Qxe3 {+10.82/16 15s} Rg6 {-2.50/8 6.8s} 41. Qc3+ {+10.96/15 15s}
Kd5 {-2.50/7 6.8s} 42. Qg7 {+19.74/17 14s} Rc6 {-2.75/8 7.7s}
43. Qxh7 {+21.26/14 14s} Kxc5 {-2.75/7 4.9s} 44. Qg7 {+23.58/16 14s}
Rxh6+ {-6.30/7 4.9s} 45. Qxh6 {+24.52/18 13s} b5 {-6.70/7 4.8s}
46. Qxa6 {+26.88/21 13s} c6 {-7.60/8 4.7s} 47. Qa7+ {+27.04/20 13s}
Kc4 {-7.60/6 4.6s} 48. Qb7 {+27.27/20 12s} Kc5 {-7.90/8 4.6s}
49. Qe7+ {+25.66/18 12s} Kd5 {-7.90/6 4.5s} 50. Qd7+ {+27.28/22 12s}
Kc5 {-8.10/6 4.5s} 51. Qe6 {+28.53/22 12s} Kb6 {-8.10/7 4.4s}
52. Qxe4 {+30.09/23 11s} Kc5 {-8.75/7 4.3s} 53. Qe5+ {+27.77/22 11s}
Kc4 {-8.75/6 4.3s} 54. Kg2 {+27.93/22 11s} c5 {-8.75/7 4.2s}
55. Qe2+ {+28.02/19 11s} Kc3 {-9.10/7 4.2s} 56. Qxb5 {+53.91/21 10s}
c4 {-9.50/7 4.1s} 57. a4 {+M19/19 10s} Kd4 {-9.50/7 4.1s} 58. a5 {+M17/18 9.8s}
c3 {-10.00/8 4.0s} 59. a6 {+M15/17 9.6s} Ke3 {-16.90/7 4.0s}
60. a7 {+M9/16 9.3s} Kd2 {-M8/7 4.0s} 61. a8=Q {+M7/15 9.1s}
Kc1 {-M6/6 3.9s, White makes an illegal move: a7a8Q} 0-1

[Event "?"]
[Site "?"]
[Date "2024.04.14"]
[Round "?"]
[White "Kojiro v0.1"]
[Black "Athene v0.1"]
[Result "0-1"]
[FEN "rnbqkb1r/ppp2ppp/5n2/3pp3/8/3PP3/PPPNNPPP/R1BQKB1R b KQkq - 3 4"]
[PlyCount "95"]
[SetUp "1"]
[Termination "illegal move"]
[TimeControl "900+3"]

1... Bg4 {+0.40/6 33s} 2. c4 {-0.57/12 21s} Nc6 {+0.35/6 32s}
3. cxd5 {-0.38/12 21s} Nxd5 {+0.45/6 31s} 4. a3 {-0.15/12 22s} Bd6 {+0.50/6 30s}
5. h3 {-0.02/12 22s} Be6 {+0.40/6 29s} 6. Ng3 {+0.07/12 22s} f5 {+0.70/6 28s}
7. e4 {+0.11/12 22s} fxe4 {+0.55/6 28s} 8. dxe4 {+0.11/11 23s} Nf4 {+0.55/6 27s}
9. Nf3 {-0.07/10 23s} Qf6 {+0.60/5 26s} 10. Qc2 {-0.29/11 23s}
Nxh3 {+0.50/5 25s} 11. Ba6 {-0.17/11 23s} Nb4 {+1.10/6 24s}
12. axb4 {+0.77/13 23s} bxa6 {+0.50/6 24s} 13. Rxh3 {+0.76/12 23s}
Bxh3 {+1.10/6 23s} 14. Bg5 {+1.30/13 23s} Bxb4+ {+1.10/7 22s}
15. Ke2 {+1.31/12 22s} Qb6 {+1.10/6 22s} 16. gxh3 {+1.42/13 22s}
Qb5+ {+1.00/6 21s} 17. Qd3 {+1.44/13 22s} Bd6 {+0.90/7 20s}
18. Qxb5+ {+2.08/14 22s} axb5 {+0.10/7 20s} 19. Nf5 {+1.99/14 22s}
g6 {+0.70/6 19s} 20. Nxd6+ {+3.92/16 21s} cxd6 {-0.15/7 19s}
21. Rd1 {+4.01/16 21s} Kd7 {-0.40/7 18s} 22. Nxe5+ {+4.49/15 21s}
Ke6 {-0.40/7 18s} 23. Nf3 {+4.51/14 21s} a6 {-0.50/7 17s} 24. Rd5 {+4.92/13 20s}
Rab8 {-0.60/7 17s} 25. Bf4 {+5.81/15 20s} Rb6 {-1.45/7 16s}
26. Ng5+ {+5.99/14 20s} Kd7 {-2.45/7 16s} 27. Bxd6 {+6.13/16 19s}
Kc8 {-2.40/7 15s} 28. Be5 {+6.51/14 19s} Re8 {-2.45/7 15s}
29. Nf7 {+7.18/16 19s} Kb7 {-2.40/7 15s} 30. Nd6+ {+7.13/16 18s}
Rxd6 {-2.35/9 14s} 31. Bxd6 {+7.31/17 18s} Rxe4+ {-2.35/7 14s}
32. Kf3 {+7.18/15 18s} Rh4 {-2.40/8 14s} 33. Kg3 {+7.44/16 17s}
Kc6 {-2.45/8 13s} 34. Kxh4 {+8.71/19 17s} Kxd5 {-2.45/9 13s}
35. Bf8 {+9.42/21 17s} Ke4 {-2.50/9 12s} 36. Kg5 {+9.73/23 16s}
Kf3 {-3.30/9 12s} 37. Bc5 {+10.11/22 16s} Kg2 {-3.40/9 12s}
38. h4 {+10.60/24 16s} Kh3 {-3.40/9 12s} 39. b4 {+13.01/22 15s}
Kh2 {-3.40/9 11s} 40. Kh6 {+14.71/23 15s} Kh3 {-3.40/10 11s}
41. Be7 {+29.92/24 15s} Kg4 {-3.50/10 11s} 42. Kxh7 {+30.20/23 14s}
Kf3 {-3.50/9 10s} 43. Kxg6 {+40.13/24 14s} Kf4 {-9.95/9 10s}
44. h5 {+41.03/23 14s} Ke5 {-12.30/9 10.0s} 45. h6 {+41.60/22 13s}
Ke6 {-13.40/9 9.8s} 46. Bc5 {+41.64/20 13s} a5 {-14.35/9 9.5s}
47. h7 {+M15/19 13s} axb4 {-14.35/8 9.3s} 48. h8=Q {+M11/18 12s}
Kd7 {-14.40/7 9.1s, White makes an illegal move: h7h8Q} 0-1