MayhemDuck 1.6: bad move message

[twoplan]

Recently I played this game against MayhemDuck 1.6 and got the message from the screenshot after my 27th move:

[Event "Computer Chess Game"]
[Site "Home"]
[Date "2022.12.05"]
[Round "-"]
[White "TwoPlan"]
[Black "MayhemDuck 1.6 (UCI2WB)"]
[Result "*"]
[TimeControl "40/300"]
[Variant "duck"]
[Annotator "1... -0.16"]

1. e4,e6 Nf6,c3 2. e5,d5 Ne4,c4 3. d4,d6 e6,b5 4. f3,g5 Nd6,e7 5. exd6,f6 Bxd6,d2 6. c3,f8 Nc6,d5 7. Bb5,f8 a6,c4 8. Bxc6,d2 dxc6,d5 9. Bg5,f6 Be7,d5 10. Bxe7,e2 Qxe7,f4 11. Ne2,f8 Qg5,f1 12. Nd2,g4 O-O,d5 13. O-O,d7 Rd8,d5 14. f4,d7 Qg6,f5 15. Nf3,e5 Bd7,d5 16. Ne5,f5 Qh5,a4 17. Ng3,f3 Qh4,a4 18. Qd3,g4 h6,c4 19. Rae1,g4 Be8,a1 20. Qf3,g5 Rd5,a1 21. Re4,g5 Rad8,a1 22. f5,g5 f6,f4 23. fxe6,g5 a5,f4 24. e7,g5 Rb8,f4 25. Ng6,g5 Bxg6,f4 26. e8=Q,f7 Rxe8,f4 27. Rxe8,f7 *

Don't know if gui or engine is responsible for the bug.

[SamuraiDangyo]

Thanks for the report!
I tried to reproduce the crash but couldn't. MayhemDuck plays normally. I think it could be the "judge" engine. As "e7e8;h5q" after this promotion. But I tried to handle all variations of promotions now v1.7 + some improvements. If MayhemDuck was crashing. Not 100% sure.

position fen 4r1k1/1pp3p1/2p2pbp/p2r4/3PR*1q/2P2Q2/PP4PP/5RK1 w - - 0 1 moves e4e8,e8f7
go btime 1000000
info depth 1 nodes 3849 time 1 nps 3849000 score cp -230 pv g8h7@e4
info depth 2 nodes 134537 time 19 nps 7080894 score cp -25 pv g8h7@c4
info depth 3 nodes 508132 time 51 nps 9963372 score cp -75 pv g8h7@a1
info depth 4 nodes 193074264 time 18545 nps 10411122 score cp -106 pv a5a4@f8
info depth 5 nodes 213835159 time 20474 nps 10444229 score cp -114 pv a5a4@f8
info depth 6 nodes 235286750 time 22449 nps 10480945 score cp -111 pv a5a4@f8
info depth 7 nodes 298393060 time 28103 nps 10617836 score cp -111 pv a5a4@f8
info depth 8 nodes 413237083 time 38457 nps 10745432 score cp -111 pv a5a4@f8
bestmove a5a4@f8

[twoplan]

Same issue with version 1.7 ... seems indeed related to promotion. I was using mayhemduck-1.7-x86-windows-64bit.exe

[Event "Computer Chess Game"]
[Site "Home"]
[Date "2022.12.09"]
[Round "-"]
[White "TwoPlan"]
[Black "MayhemDuck 1.7 (UCI2WB)"]
[Result "*"]
[TimeControl "40/300"]
[Variant "duck"]
[Annotator "1... -0.16"]

1. e4,e6 Nf6,c3 2. e5,d5 Ne4,c4 3. d4,d6 e6,b5 4. f3,g5 Nd6,e7 5. exd6,d2
   Bxd6,e2 6. Bf4,e5 Qh4,g3 7. Bxd6,f2 cxd6,d2 8. g3,f4 Qf6,c3 9. Ne2,f5
   O-O,f4 10. Nbc3,f5 Qg5,g2 11. Ne4,f5 Qe3,g2 12. Qd3,f4 Qxf3,e3 13. Nf4,g2
   Nc6,e3 14. Nxd6,g2 e5,e3 15. dxe5,g2 Nxe5,e4 16. Qxf3,d1 Nxf3,c4 17.
   O-O-O,g2 b5,e2 18. Bg2,b7 Ne5,f3 19. Rhe1,b7 b4,e4 20. Nxc8,b8 Rxc8,e4 21.
   Kb1,b7 Rc5,d5 22. Rd4,b8 Rc4,d5 23. Rxc4,b8 Nxc4,e4 24. b3,b8 Nd2,c1 25.
   Kb2,b8 a5,d5 26. Re8,b8 g5,f8 27. Rxa8,e8 gxf4,c8 28. gxf4,g7 d6,c8 29.
   Rxa5,g7 Ne4,f3 30. Ra8,g7 Nc3,e8 31. f5,g7 Nd1,b8 32. Kc1,c3 Ne3,c8 33.
   Be4,g7 d5,b8 34. Kd2,f1 Nc4,e8 35. bxc4,g7 dxe4,b8 36. f6,g7 h6,e8 37.
   c5,h7 h5,c8 38. c6,h7 h4,c8 39. c7,h7 h3,c8 40. Ke3,h7 Kf8,c8 41. Kxe4,e8
   Kg8,c8 42. Rb8,h7 Kh8,c8 43. Rxb4,h7 Kg8,c8 44. a4,h7 Kf8,g8 45. c8=Q,e8
   Kg8,f8 46. Kf5,h7

[SamuraiDangyo]

I finally found and fixed the crash. See v1.8. MayhemDuck worked flawlessly but WinBoard sent bad moves:

 76 Move: e6c6,c6c3
 77 Move: e5c6,c6b7
 78 Move: f4f3,f3c3
 79 Move: c6e5,e5a8
 80 Move: f3f2,f2f1
 81 Move: e5f7,f7a8
 82 Move: f2f1,f1c3qf7h6,h6g7
 83 Move: f7h6,h6g7
 84 Move: g8h7,h7g4
 85 Cmd: position
 86 Cmd: go
 87 Cmd: quit

[twoplan]

Thanks for the new MayhemDuck!
It feels weaker than the previous versions. The move 16. .. Bxh3 was surprising, but 20. ..Kd8 with duck to d4 (??) leads to an immediate loss.

Is the final illegal move message after my king capture to be expected?

[SamuraiDangyo]

Hello.
I noticed it too. I played test games vs DuckSlayer and saw these blunders. 1.9 is stronger than 1.8 but I don't think much. It all comes down to ease of testing.
Illegal move (0000) message is due Winboard sending moves after the king is captured.