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While chess problems and such are usually meant for Puzzling Stack Exchange, I thought that this one should be an exception since it’s more relevant IMHO.

Resetting the 50-move rule, i.e. restart the 100 ply cycle, requires either a pawn push or a capture. Checkmate does not restart it of course.

[Title "Geir Sune Tallaksen Østmoe, MatPlus.net Forum 8/14/2013, White To Move"]
[FEN "1K6/2p5/p5pr/q2k3n/P1pPp1rP/1pP1PpPR/1P3P1B/3N3N w - - 0 1"]

Given that White is playing to reset the 50-move rule and Black is trying to avoid it, how many moves will it take to for White to reset the 50-move rule? Or, in layman’s terms, after how many moves can White make a capture or a pawn moves while Black avoids doing or allowing that to happen?

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  • Do I understand correctly that the question is: after how many moves can white force black to capture?
    – user1583209
    Apr 7, 2020 at 17:08
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    Ok, so there are two factors that make this problem possible to solve I guess. First, after 1. Kc8, black can only move the h6 rook to avoid resetting the counter. Secondly, white can free the rook through the maneouvre Bg1-Rh2-Rg2-Bh2-Rg1-Re1-Re2-Rc2-Rc1-Ra1-Ra3, threatening Rxb3 resetting the counter. Left is to calculate for how long black can give checks with the rook, and thus delaying the rook maneouvre. I'm too lazy to do such things myself though.
    – Scounged
    Apr 8, 2020 at 2:22
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    @Scounged: I am also too lazy, but the problem might be slightly more interesting (and harder to count), because also the Nh5 can check in some lines. For instance if the white king runs straight towards the right, you can have a setup with Rh7 and the knight checking from f6 and d7 while the white king shuffles between g8 and f8. Of course this perpetual can be broken by e.g. moving the king to d8. Just wanted to say that it is more work than just checking with the rook from the sides.
    – user1583209
    Apr 8, 2020 at 8:07
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    @Scounged: furthermore, if you can move the knight with check, you also have the option of transferring the knight to another square, while the black rook blocks the pawn from h5.
    – user1583209
    Apr 8, 2020 at 8:09
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    Who says that chess problems are usually meant for Puzzling Stack Exchange? I'm sure they are totally on topic here in good old chess.stackexchange.com
    – Laska
    Apr 25, 2020 at 18:24

2 Answers 2

Reset to default
1

Since no one has managed to solve this problem entirely, here is the answer. Credit goes to @NoseKnowsAll and @Scrounged in the comments for identifying the mechanism White uses to force the reset. This answer merely shows how White can avoid a perpetual check by Black.

[Title "Geir Sune Tallaksen Østmoe, MatPlus.net Forum 8/14/2013, White To Move"]
[FEN "1K6/2p5/p5pr/q2k3n/P1pPp1rP/1pP1PpPR/1P3P1B/3N3N w - - 0 1"]

1. Kc8 Rh8+ 2. Kd7 Rh7+ 3. Ke8 Rh8+ 4. Kf7 Rh7+ 5. Kg8 Nf6+ 6. Kf8 Nd7+ 7. Ke8 Nf6+ 8. Kd8 Nh5 9. Bg1 Rh8+ 10. Kd7 Rh7+ 11. Ke8 Rh8+ 12. Kf7 Rh7+ 13. Kg8 Nf6+ 14. Kf8 Nd7+ 15. Ke8 Nf6+ 16. Kd8 Nh5 17. Rh2 Rh8+ 18. Kd7 Rh7+ 19. Ke8 Rh8+ 20. Kf7 Rh7+ 21. Kg8 Nf6+ 22. Kf8 Nd7+ 23. Ke8 Nf6+ 24. Kd8 Nh5 25. Rg2 Rh8+ 26. Kd7 Rh7+ 27. Ke8 Rh8+ 28. Kf7 Rh7+ 29. Kg8 Nf6+ 30. Kf8 Nd7+ 31. Ke8 Nf6+ 32. Kd8 Nh5 33. Bh2 Rh8+ 34. Kd7 Rh7+ 35. Ke8 Rh8+ 36. Kf7 Rh7+ 37. Kg8 Nf6+ 38. Kf8 Nd7+ 39. Ke8 Nf6+ 40. Kd8 Nh5 41. Rg1 Rh8+ 42. Kd7 Rh7+ 43. Ke8 Rh8+ 44. Kf7 Rh7+ 45. Kg8 Nf6+ 46. Kf8 Nd7+ 47. Ke8 Nf6+ 48. Kd8 Nh5 49. Re1 Rh8+ 50. Kd7 Rh7+ 51. Ke8 Rh8+ 52. Kf7 Rh7+ 53. Kg8 Nf6+ 54. Kf8 Nd7+ 55. Ke8 Nf6+ 56. Kd8 Nh5 57. Re2 Rh8+ 58. Kd7 Rh7+ 59. Ke8 Rh8+ 60. Kf7 Rh7+ 61. Kg8 Nf6+ 62. Kf8 Nd7+ 63. Ke8 Nf6+ 64. Kd8 Nh5 65. Rc2 Rh8+ 66. Kd7 Rh7+ 67. Ke8 Rh8+ 68. Kf7 Rh7+ 69. Kg8 Nf6+ 70. Kf8 Nd7+ 71. Ke8 Nf6+ 72. Kd8 Nh5 73. Rc1 Rh8+ 74. Kd7 Rh7+ 75. Ke8 Rh8+ 76. Kf7 Rh7+ 77. Kg8 Nf6+ 78. Kf8 Nd7+ 79. Ke8 Nf6+ 80. Kd8 Nh5 81. Ra1 Rh8+ 82. Kd7 Rh7+ 83. Ke8 Rh8+ 84. Kf7 Rh7+ 85. Kg8 Nf6+ 86. Kf8 Nd7+ 87. Ke8 Nf6+ 88. Kd8 Nh5 89. Ra3 Rh8+ 90. Kd7 Rh7+ 91. Ke8 Rh8+ 92. Kf7 Rh7+ 93. Kg8 Nf6+ 94. Kf8 Nd7+ 95. Ke8 Nf6+ 96. Kd8 Rh8+ 97. Ke7 Ng8+ 98. Kf7 Nh6+ 99. Kg7 Rg8+ 100. Kxh6
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White can get the rook out of the cage, and then it could threaten a capture. However, Black may attempt a perpetual check.

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