Start Your Engines

[Spliffjiffer]

as white has to loose 1 tempo anyways you are right...u can loose this tempo already earlier (with chest's moves 3.ke2, 4.ke3 eg)...so far so good but i believe that your parameter settings might have been too restrictive...i can err of course but my analysis ends in a mate in 34 also...quite incredible

[Paloma]

35# checked with backwards-Analysis.

e.g. with Parameter *RetroAnalysis*

[zullil]

35# checked with backwards-Analysis.

e.g. with Parameter *RetroAnalysis*

Suppose White announces that he will play

1. Kg2 2. Kf3 3. Ke4 4. Kd5 5. Kc5 6. Kb6 7. Kxa6 8. Kxa5 9. Kxa4 10. Kxa3 11. Kb4 12. a4 13. a5 14. a6 15. a7

no matter what moves Black makes.

What configuration of K, R, R should Black have in place prior to White's move 16 to survive the longest?

[Spliffjiffer]

inspired by your "chest approach"...and i must say that chest is really impressively fast here with adequate settings, its just unbelievable, i would have saved a lot of time by investigating with "normal" programs...i came across following settings:
chest-uci-settings: hashsize=512; problem type=mate; search depth=34; all solutions=enabled; use database=disabled; search mode=special; CO=0; TD=0; TR=3; KS=3; PL=3; MM=6; SO=KPX (and ExpertOptions= -rS)

with these settings chest finds 3 mates with mate in 34 (Kg1,Kh1,Kg2) within around 1:30 min...can so confirm or refute this ?

this is the FEN btw again;
4b1kn/3p1p1r/p2P1Ppr/p5Pp/p6P/p7/P7/7K w - - 0 1

and thx for your "chest-hint" Herbert !

[Ovyron]

Wait, what? Are people really discussing this and giving away the answer before the contest it over?

Anyway, here's Stockfish PA GTB output, it's a special version able to learn scores of positions and backsolve them to the root, and keep them in a file that is loaded, so the next time the engine is fired up, it remembers what it has learned.

And this is its output for the position:

32/02 0:01 +M34 1.Kg2 Rg7 2.Kf3 Rgh7 3.Ke4 Rg7 4.Kd5 Rgh7 5.Kc5 Rg7 6.Kb6 Rgh7 7.Kxa6 Rg7 8.Kxa5 Rhh7 9.Kxa4 Rh6 10.Kxa3 Rhh7 11.Kb4 Rh6 12.a4 Rgh7 13.a5 Rg7 14.a6 (4.407.040) 2365
33/02 0:02 +M34 1.Kg2 Rg7 2.Kf3 Rgh7 3.Ke4 Rg7 4.Kd5 Rgh7 5.Kc5 Rg7 6.Kb6 Rgh7 7.Kxa6 Rg7 8.Kxa5 Rhh7 9.Kxa4 Rh6 10.Kxa3 Rhh7 11.Kb4 Rh6 12.a4 Rgh7 13.a5 Rg7 14.a6 (6.772.313) 2499
34/02 0:03 +M34 1.Kg2 Rg7 2.Kf3 Rgh7 3.Ke4 Rg7 4.Kd5 Rgh7 5.Kc5 Rg7 6.Kb6 Rgh7 7.Kxa6 Rg7 8.Kxa5 Rhh7 9.Kxa4 Rh6 10.Kxa3 Rhh7 11.Kb4 Rh6 12.a4 Rgh7 13.a5 Rg7 14.a6 (9.682.435) 2590
35/02 0:05 +M34 1.Kg2 Rg7 2.Kf3 Rgh7 3.Ke4 Rg7 4.Kd5 Rgh7 5.Kc5 Rg7 6.Kb6 Rgh7 7.Kxa6 Rg7 8.Kxa5 Rhh7 9.Kxa4 Rh6 10.Kxa3 Rhh7 11.Kb4 Rh6 12.a4 Rgh7 13.a5 Rg7 14.a6 (15.748.528) 2648
36/02 0:09 +M34 1.Kg2 Rg7 2.Kf3 Rgh7 3.Ke4 Rg7 4.Kd5 Rgh7 5.Kc5 Rg7 6.Kb6 Rgh7 7.Kxa6 Rg7 8.Kxa5 Rhh7 9.Kxa4 Rh6 10.Kxa3 Rhh7 11.Kb4 Rh6 12.a4 Rgh7 13.a5 Rg7 14.a6 (26.390.643) 2650
37/02 0:14 +M34 1.Kg2 Rg7 2.Kf3 Rgh7 3.Ke4 Rg7 4.Kd5 Rgh7 5.Kc5 Rg7 6.Kb6 Rgh7 7.Kxa6 Rg7 8.Kxa5 Rhh7 9.Kxa4 Rh6 10.Kxa3 Rhh7 11.Kb4 Rh6 12.a4 Rgh7 13.a5 Rg7 14.a6 (37.088.650) 2598
38/02 0:15 +M34 1.Kg2 Rg7 2.Kf3 Rgh7 3.Ke4 Rg7 4.Kd5 Rgh7 5.Kc5 Rg7 6.Kb6 Rgh7 7.Kxa6 Rg7 8.Kxa5 Rhh7 9.Kxa4 Rh6 10.Kxa3 Rhh7 11.Kb4 Rh6 12.a4 Rgh7 13.a5 Rg7 14.a6 (40.845.109) 2586

[Paloma]

Wait, what? Are people really discussing this and giving away the answer before the contest it over?

I responce only to Dann's posting here
http://www.talkchess.com/forum/viewtopi ... 65&t=66359
and Vincent above too, where they give the solution.

[Paloma]

Hi Peer,

With MM=6 Chest choose the bad black move 23... Rg8 (34# for white), instead of better defending move 23...Kg8
what allows white only a matt in 35 !!

Set MM to 4 and you get mate in 35

[pgn]
[Event "?"]
[Site "?"]
[Date "2018.01.24"]
[Round "?"]
[White "?"]
[Black "?"]
[Result "*"]
[SetUp "1"]
[FEN "4b1kn/3p1p1r/p2P1Ppr/p5Pp/p6P/p7/P7/7K w - -"]

1. Kh2 Rg7 2. Kg2 Rhh7 3. Kf2 Rh6 4. Ke3 Rhh7 5. Kd4 Rh6
6. Kc5 Rhh7 7. Kb6 Rh6 8. Kxa6 Rhh7 9. Kxa5 Rh6 10. Kxa4
Rhh7 11. Kxa3 Rh6 12. Ka4 Rhh7 13. Ka5 Rh6 14. a4 Rhh7
15. Kb6 Rh6 16. a5 Rhh7 17. a6 Rh6 18. a7 Kh7 19. a8=Q Rg8
20. Qa5 Rf8 21. Qe5 Rg8 22. Kc7 Rf8 23. Kd8 Kg8 (23... Rg8
24. Qxe8 Rxe8+ 25. Kxe8 Kg8 26. Kxd7 Rh7 27. Ke7 Rg7
28. fxg7 f6 29. gxh8=Q+ Kxh8 30. Kf7 Kh7 31. d7 fxg5
32. hxg5 h4 33. d8=Q h3 34. Qg8#) 24. Qxe8 Rh7 25. Qxf8+
Kxf8 26. Kxd7 Rg7 27. Kd8 Rh7 28. d7 Rh6 29. Kc8 Kg8
30. d8=Q+ Kh7 31. Qd6 Kg8 32. Kd8 Rh7 33. Ke8 Rg7 34. Qf8+
Kh7 35. Qxg7# [/pgn]

Click in Engine properties on AutoSolution and you got this:

WinCHEST Ver.3.19i+, 08-Mar-2011
Options = -M1024 -Z35 -el -U -K3 -P3 -X4 -00 -5 -rS
Input file: STDIN
Reading job:
% created by ChestUCI Ver.5.2
W: Kh1 Pa2 Pd6 Pf6 Pg5 Ph4 (6)
B: Kg8 Rh7 Rh6 Be8 Nh8 Pa6 Pa5 Pa4 Pa3 Pd7 Pf7 Pg6 Ph5 (13)
FEN: 4b1kn/3p1p1r/p2P1Ppr/p5Pp/p6P/p7/P7/7K w - -
analysing (special-mate in 35 moves):
Solution (in 35 moves):
h1g1
h1h2
h1g2
Time (virt) = 45.062 sec

PV= h1g1 h7g7 g1f1 h6h7 f1f2 h7h6 f2e3 h6h7 e3d4 h7h6 d4c5 h6h7 c5b6 h7h6 b6a6 h6h7 a6a5 ... (snip)
PV= h1h2 h7g7 h2g2 h6h7 g2f2 h7h6 f2e3 h6h7 e3d4 h7h6 d4c5 h6h7 c5b6 h7h6 b6a6 ... (snip)
PV= h1g2 h7g7 g2f2 h6h7 f2e2 h7h6 e2e3 h6h7 e3d4 h7h6 d4c5 h6h7 c5b6 h7h6 b6a6 ... (snip)
h1g1 g8f8 g1f1 ...+33
____ h7g7 g1f1 ...+33
h1g2 g8f8 g2f2 ...+33
____ h7g7 g2f2 ...+33
h1h2 g8f8 h2g2 ...+33
____ h7g7 h2g2 ...+33

end of solution tree (no duals except at top)
Total Time (virt) = 45.063 sec

[Spliffjiffer]

hi Herbert

24.Qxe8 is mate in 11...tested with chest "brute force" (normal-mode)...problem in your line is 25.Qxf8 ??...25.Kxd7 ! mates 1 move earlier

[zullil]

35# checked with backwards-Analysis.

e.g. with Parameter *RetroAnalysis*

Suppose White announces that he will play

1. Kg2 2. Kf3 3. Ke4 4. Kd5 5. Kc5 6. Kb6 7. Kxa6 8. Kxa5 9. Kxa4 10. Kxa3 11. Kb4 12. a4 13. a5 14. a6 15. a7

no matter what moves Black makes.

What configuration of K, R, R should Black have in place prior to White's move 16 to survive the longest?

[D] 4brkn/P2p1p2/3P1Ppr/6Pp/1K5P/8/8/8 w - - 1 16

Seems like this configuration is optimal for Black after the first 15 moves by White given above. According to Cfish, this position is mate in no more than 19 moves.

Code: Select all

Mate in 19 16. a8=Q Rh7 17. Kc5 Rg7 18. Qe4 Rh7 19. Qe7 Rg7 20. Qe5 Rh7 21. Kb6 Rh6 22. Kc7 Kh7 23. Kd8 Rg8 24. Qxe8 Rxe8+ 25. Kxe8 Kg8 26. Kxd7 Kf8 27. Kc7 Kg8 28. d7 Kh7 29. Kd6 Kg8 30. d8=Q+ Kh7 31. gxh6 g5 32. Qf8 Kg6 33. Ke5 gxh4 34. Qg7# (depth 104, 0:02:51)

Thus it seems that White can force mate in no more than 34 moves from the original position.

[Paloma]

It's not my Line, it's Chest's Line.

You're right, 25.Kd7 mates earlier.