Difficult positions

[Matthies]

r1b2k1r/1pp1npp1/2qp3p/p7/P2b3P/1P1B1PP1/R4NK1/2BQR3 w - - 0 22
Rubi misses Bc4 (master 28.8.2021, depth 51)... finds it at depth 52 after 16min.
Master 22.01.2022 finds it immediately.

5k2/p3r1p1/1p2Bpb1/q1pPr2p/P1P1P2P/4R1P1/2Q5/5RK1 w - - 0 39
Rubi doesn't find the winning move g3g4 (from TCEC cup9 match against SlowChess)
Master 22.01.2022 finds it at depth 41 (2:40 on 1 thread).

8/2k4p/6p1/5p1P/p1PQq3/P7/5PPK/8 w - - 9 49
From https://www.chess.com/computer-chess-championship#event=ccc-16-rapid-semifinals&game=199
Rubi doesn't want the queens exchange although the remaining pawns-only endgame is won and SF finds a +8 score at depth 28.

8/p6p/4k3/3N1p2/1Br2P2/4PB2/1b3K1P/8 w - - 1 30
Rubi has difficulties to find winning move Bd1
Master 22.01.2022 finds it at depth 45 (5:30 on 1 thread).

1r4r1/3q1npk/2b1pbnp/Rp1p4/1N1P3P/2PQ1pP1/1K3B2/5B1R w - - 0 1
Rubi misses Qxg6+ (M15)

[Event "TCEC Season 22 - League 1"]
[Site "https://tcec-chess.com"]
[Date "2022.03.04"]
[Round "25.3"]
[White "Revenge 20220211"]
[Black "RubiChess 20220223"]
[Result "1-0"]
[Annotator "archive"]

1. e4 d5 2. exd5 Qxd5 3. Nc3 Qa5 4. d4 c6 5. Bc4 Bf5 6. g4 Be4 7. Nf3 Bd5 8. b4 Qxb4 9. Bxd5 cxd5 10. Qd3 Qc4 11. Qxc4 dxc4 12. Rb1 b6 13. Rb4 Nc6 14. Rxc4 Na5 15. Rc7 e6 16. d5 Nf6 17. dxe6 fxe6 18. Nd4 Bd6 19. Rxg7 Be5 20. Ncb5 Nd5 21. Rg5 Bf6 22. Rh5 Kd7 23. Nb3 Rac8 24. Nxa5 bxa5 25. Na3 Be7 26. O-O Bxa3 27. Bxa3 Rxc2 28. h3 h6 29. Bc1 Rxa2 30. Bxh6 a6 31. Rc1 Ra3 32. Rc4 Rb3 33. Ra4 Rb5 34. Rh4 Nb6 35. Ra1 e5 36. Kh2 Nc4 37. Rc1 Nd6 38. Rc2 Nf7 39. Bg5 Rxh4 40. Bxh4 Nd6 41. Bg3 a4 42. Ra2 Ra5 43. h4 a3 44. h5 Ke6 45. f3 Ra4 46. Kh3 a5 47. Be1 Nb5 48. h6 Kf7 49. Bg3 e4 50. Be5 Kg6 51. f4 Nd4 52. Bg7 Kf7 53. Bxd4 Rxd4 54. g5 Kg6 55. Kg4 e3 56. Rc2 a2 57. Rxa2 Re4 58. Kf3 Re8 59. Rc2 Re7 60. Rh2 Re8 61. h7 Rh8 62. Kxe3 Kg7 63. f5 Kf7 64. g6+ Kf6 65. Kf4 a4 66. Re2 a3 67. Re6+ Kg7 68. Kg5 Kf8 69. Kf6 Rxh7 70. gxh7
*

Somewhere at
8/8/4k2P/pn2p3/r5P1/p4P1K/R7/4B3 b - - 0 48
Rubi 20220223 misses something. Not seeing 52. Bg7 for too long time seems the main problem.

https://www.chess.com/computer-chess-championship#event=ccc-17-bullet-main&game=404
8/2r5/7P/P3N3/4nk2/7B/8/5K2 w - - 7 158
Rubi-20220223 plays Nd3+ (instead of Ng6) not seeing that the following Kg3 (Rubi prefers Kg5) almost immediately wins.
Some moves later:
8/4r3/7P/P2B4/4n3/3N2k1/8/5K2 b - - 9 158
Rubi doesn't see mate in 9.

Another bad CCC game. Around move 28 Rubi starts to play very bad.

[Event "CCC 17 Bullet: Main (2|1)"]
[Site "?"]
[Date "2022.04.17"]
[Round "1"]
[White "SlowChess"]
[Black "Rubi"]
[Result "1-0"]
[ECO "D10"]
[GameDuration "00:06:39"]
[GameEndTime "2022-04-17T02:26:07.320 PDT"]
[GameStartTime "2022-04-17T02:19:28.230 PDT"]
[Opening "QGD Slav defense"]
[PlyCount "149"]
[TimeControl "120+1"]

1. d4 d5 2. c4 c6 3. Nc3 Nf6 4. e3 g6 5. Nf3 Bg7 6. Be2 O-O 7. O-O b6 8. a4 a5
9. cxd5 Nxd5 10. e4 Nb4 11. Be3 N8a6 12. h3 Be6 13. Qc1 Nc7 14. Rd1 Ne8 15. Rd2
Nd6 16. Qf1 Qd7 17. Bf4 Qb7 18. Ng5 Bd7 19. Qd1 Rad8 20. Rc1 h6 21. Nf3 Kh7 22.
Bf1 Be6 23. b3 Rc8 24. Ne5 f5 25. exf5 Nxf5 26. Qg4 Bxe5 27. Bxe5 Bxb3 28. Ne2
Nd5 29. h4 h5 30. Qg5 Qd7 31. Nf4 Nxf4 32. Bxf4 Qe6 33. Be5 c5 34. Bd3 c4 35.
Be4 c3 36. Re2 Bc4 37. Re3 Bd5 38. Bd3 Qf7 39. f3 Rc6 40. g4 hxg4 41. fxg4 Ng7
42. Rf1 Rf6 43. Bxf6 exf6 44. h5 fxg5 45. hxg6+ Kg8 46. gxf7+ Rxf7 47. Bb5 Rc7
48. Rc1 c2 49. Re2 Bb3 50. d5 Bxd5 51. Rexc2 Rxc2 52. Rxc2 Ne6 53. Bc6 Bb3 54.
Rb2 Bc4 55. Rxb6 Kf7 56. Bb5 Bd5 57. Ra6 Ke7 58. Rxa5 Kd6 59. Kf2 Nc5 60. Ra7
Ne6 61. a5 Nc7 62. Be2 Bc6 63. a6 Ne6 64. Rf7 Nd8 65. Rg7 Ne6 66. Rg6 Be4 67.
Rxe6+ Kxe6 68. Bf3 Bc2 69. a7 Kf6 70. a8=Q Kg7 71. Bd5 Bh7 72. Qa1+ Kg6 73. Qe5
Bg8 74. Bxg8 Kh6 75. Qf6# 1-0

r1bq1rk1/pp1nbppp/4p3/1N1pP1P1/1n3P2/1N1BB3/PPP4P/R2QK2R w KQ - 1 14
Rubi needs a long time to find Bxh7

2k5/Bp2p3/2pn1b2/P1Np4/1PqPp1br/2P1P1QN/2R2PP1/4K3 b - - 1 33
Rubi doesn't find (or needs very long to find) winning e5

1r3r1k/8/pB1p2n1/P2Pp1qp/4PpPb/3B4/3QN1PK/R4R2 w - - 2 30
From https://tcec-chess.com/#div=l1&game=124&season=23
Rubi has problems to find Kg1.
...
Main problem seems to find g3 at 1r3r1k/8/pB1p2n1/P2Pp1q1/4Pppb/3B4/3QN1P1/R4RK1 w - - 0 31

3r3k/1p4p1/p7/P1R1bp1p/4BP2/4P1K1/1P6/8 w - - 0 51
From https://www.chess.com/computer-chess-championship#event=bullet-throwdown-berserk-10&game=178
Rubi (20221003) switches from best move Bxb7 to worse Rxe5 at depth 34.

4b3/1p3pk1/p6p/1P2n1p1/2P5/8/P2R4/2K2B2 b - - 0 34
Rubi wants h5 which is losing. g4 or f5 is correct.
Rubi-20221008 switches to f5 at depth 55.

4q1kr/p6p/1prQPppB/4n3/4P3/2P5/PP2B2P/R5K1 w - - 0 1
Best and winning line starts with 1.Qd6xe5 f6xe5 2.Ra1-f1

Q4b1r/2pq1k1p/2n2pn1/1p1Pp1p1/8/1NP2P2/PP3P1P/R1BR2K1 b - - 0 16
Rubi doesn't see winning move Qh3 and wants to save knight on c6 instead.