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Challenge: maximize the number of moves white needs for its king to reach a square of your choosing, adhering to the following rules:

  • Black does not move.
  • Like normal: The king may not be in a position where it's in check (after a white move). It is allowed at the start to be in check.
  • The starting pieces do not exceed the normal starting material.

EDIT Extra rule: The black king cannot be attacked. Reasoning: attacking the black king with e.g. a pawn would mean black 'loses' and thus the white king will not reach its destination. I realize that this is a bit doubtful since I allow a board without a black king, but it seems most reasonable to me to treat the king like this if he is on the board.

Note: the starting pieces may be placed anywhere. It does not have to be a valid chess position; even the black king may be missing.

Clarification: This means e.g. that the two bishops may cover the same color tiles, and pawns may be on the first line. On the other hand, promoted pawns are not starting pieces, and pawns on the 8th row are excluded in line with this. Pawns can be promoted during play.

Example: A lone white king on a1 will need 7 moves to reach a8; add a black rook on the h-row and it will take 14 moves.

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  • $\begingroup$ Do you have a final answer for this? Is a final answer provable for this? $\endgroup$
    – Ben Barden
    Commented Nov 10, 2020 at 15:47
  • $\begingroup$ Can the piece trying to be moved to have a black piece on it? $\endgroup$
    – William Pennanti
    Commented Nov 10, 2020 at 15:50
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    $\begingroup$ I have no final answer, let alone a provable one. All moves are counted. (the title may be a bit misleading, but the description counts: white moves not white-king moves.) $\endgroup$
    – Retudin
    Commented Nov 10, 2020 at 15:51
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    $\begingroup$ Pawns on the first row are allowed, pawns on the 8th row not, if white ones reach it they must be promoted (such that the king reaches its destination fastest). I strongly doubt that will lead to a high number of moves though. $\endgroup$
    – Retudin
    Commented Nov 10, 2020 at 16:09
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    $\begingroup$ @O.F. The minimum moves needed(so no walking in circles), while the king may not be in a position where it's in check. (which means the king must maneuver around forbidden squares, and may need captures to free squares reachable by black pieces) $\endgroup$
    – Retudin
    Commented Nov 11, 2020 at 13:39

6 Answers 6

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4
+100
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This position with target square b7 requires 152 moves.

The position is an adaptation of Rewan Demontay's adaptation of Branko Koludrovic, Cornel Pacura & Arno Tüngler's problem, using also a black pawn on h8 as suggested by Retudin. I have only added a black pawn on a8 and changed the white king's target square from h2.

Example white moves:

1. Kf1 2. Bd2 3. Ke1 4. Bc1 5. Kd2 6. Kd3 7. Bd2 8. Be1 9. Kd2 10. Kc1 11. Ba2 12. Kb1 13. Ka1 14. Bb1 15. Ka2 16. Ka3 17. Ka4 18. Ka5 19. Ka6 20. Ka7 21. Kxa8 22. Kb8 23. Kc7 24. Kd7 25. Ke7 26. Kf8 27. Kg8 28. Kxh8 29. Kxh7 30. Kg6 31. Kh5 32. Kxg4 33. Kh5 34. Kg6 35. Kg7 36. Kf8 37. Ke7 38. Kd7 39. Kc7 40. Kb8 41. Ka7 42. Ka6 43. Ka5 44. Ka4 45. Ka3 46. Ka2 47. Ka1 48. Ba2 49. Kb1 50. Kc1 51. Kd2 52. Kd3 53. Bd2 54. Bc1 55. Kd2 56. Ke1 57. Kf1 58. Kxg1 59. Kf1 60. Ke1 61. Kd2 62. Kd3 63. Bd2 64. Be1 65. Kd2 66. Kc1 67. Kb1 68. Ka1 69. Bb1 70. Ka2 71. Ka3 72. Ka4 73. Ka5 74. Ka6 75. Ka7 76. Kb8 77. Kc7 78. Kd7 79. Ke7 80. Kf8 81. Kg7 82. Kg6 83. Kh5 84. Kg4 85. Kxh3 86. Kg4 87. Kh5 88. Kg6 89. Kg7 90. Kf8 91. Ke7 92. Kd7 93. Kc7 94. Kb8 95. Ka7 96. Ka6 97. Ka5 98. Ka4 99. Ka3 100. Ka2 101. Ka1 102. Ba2 103. Kb1 104. Kc1 105. Kd2 106. Kd3 107. Bd2 108. Bc1 109. Kd2 110. Ke1 111. Kf1 112. Kg1 113. Kxh1 114. Kg1 115. Kf1 116. Ke1 117. Kd2 118. Kd3 119. Bd2 120. Be1 121. Kd2 122. Kc1 123. Kb1 124. Ka1 125. Bb1 126. Ka2 127. Ka3 128. Ka4 129. Ka5 130. Ka6 131. Ka7 132. Kb8 133. Kc7 134. Kd7 135. Ke7 136. Kf8 137. Kg7 138. Kg6 139. Kh5 140. Kg4 141. Kxf3 142. Kg4 143. f4 144. fxe5 145. exd6 146. Kh5 147. Kg6 148. Kf7 149. Ke7 150. Kd7 151. Kc7 152. Kb7

This can be relayed here on Chess Meta.

Although not computer-verified, this position and target square give what I believe is the best improvement to Rewan Demontay's latest position when modified only by adding still-available permissible material and/or changing the target square.

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  • $\begingroup$ I do believe some extra moves can be gotten out of this: block g7. The best way I see for this is to move the knight on d6 to d8 and f6 to d6. In addition h7 can move to h6 to protect the bishop in the endgame $\endgroup$
    – Retudin
    Commented Jan 1, 2021 at 13:02
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First solution - 50 moves
Second solution - 59 moves

Current solution - 66 moves (beaten by Retudin - 70 moves and Rewan Demontay - 139 moves)

Target square is a8.

enter image description here

Moves:

enter image description here

enter image description here

enter image description here

enter image description here

enter image description here

enter image description here

enter image description here

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  • $\begingroup$ happy? PS feel free to edit my solution to link to your solution, That seems nice but I don't know how. And thx for the lichess tip. $\endgroup$
    – Retudin
    Commented Nov 12, 2020 at 19:47
  • $\begingroup$ About mine, a1 needs to be captured before the first knight, which needs a free e4. So I think my 70 is correct. About yours: If you and add white pawns on a5a6; you score several points more. 69 I think, with target square a5 $\endgroup$
    – Retudin
    Commented Nov 12, 2020 at 20:21
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This position:

enter image description here

requires the following 40 moves to move the king from a1 to b7:

1. Kb1 2. Kc1 3. Kd1 4. Ke1 5. Kf1 6. Kg1 7. Kxh2 8. Kg2 9. Kf2 10. Ke2 11. Kd2 12. Kc2 13. Kb2 14. Kxa3 15. Kb3 16. Kc3 17. Kd3 18. Ke3 19. Kf3 20. Kg3 21. Kh4 22. Kh5 23. Kh6 24. Kxh7 25. Kxh8 26. Kh7 27. Kh6 28. Kg5 29. Kxf5 30. Kxe5 31. Kxd5 32. Kxc5 33. Kxb5 34. Ka6 35. Ka7 36. Kb8 37. Kc8 38. Kxd8 39. Kc8 40. Kxb7

As a bonus, the White king is alone (fits the 'solitaire' theme'), the position is legal, and it doesn't use promoted pieces. The pawn on a5 and the bishop on h7 aren't even necessary, so there's probably room for some optimization.

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10
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Stealing ideas from Sleafar's first solution, I got to 62 moves. So hopefully someone can better that with the magic 64 or more.
EDIT: Since 62 is beaten by Sleafar, I'll up my score to 70: Earlier I failed to realize a8 could just be a pawn; freeing up a bishop

enter image description here h1 must be removed to reach a1. Doing that cost 8 moves, after which 62 moves are needed exactly like in my first solution. The top left cluster could be removed before capturing h1, but that also results in 70 moves total. Note that the pawn cannot block the bishop's line, since it is needed to block the queen's line. enter image description here The king moves from h1 to h3.
1: Capture c8 and then a7,a8,b7,a6 (14 moves)
2: Block the queen's line with the free pawn (3 moves)
3: Capture a1 and then the now unprotected d4 (16 moves)
4: Free b3 for promotion by capturing c6,b5,d5,b4,b6 (10 moves)
5: Move to e.g. g4 (5 moves)
6: promote (to queen or rook) and clear h8 (8 moves)
7: advance the pawns and move to the target square (6 moves)
Total: 14+3+16+10+5+8+6 = 62 moves

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  • $\begingroup$ On Lichess you can mark fields and draw arrows using the right mouse button. Be careful, clicking with the left mouse button deletes all marks. By holding Ctrl and/or Alt you can change the color. $\endgroup$
    – Sleafar
    Commented Nov 11, 2020 at 20:03
  • $\begingroup$ Your turn ;) $\endgroup$
    – Sleafar
    Commented Nov 12, 2020 at 17:19
  • $\begingroup$ @Sleafar (h8 blocks e5 and) h1 blocks e4 so h1 has to be captured to reach a1. it takes 26 moves to reach d6 after capturing the 5 top left pieces and h1, no matter which corner is done first. $\endgroup$
    – Retudin
    Commented Nov 12, 2020 at 20:35
  • $\begingroup$ I think you are right. Will try tomorrow to improve my score again. ;) $\endgroup$
    – Sleafar
    Commented Nov 12, 2020 at 21:22
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Addendum #2: With @Retudin's suggestion of placing an additional Black pawn on the bank tank, to the 129-mover, and my idea of moving around a few pieces, we have here a new record of 135 moves, with the king starting in check. The solution is still inherently the same, so there is no need to put it in.

Further Edit: Since there is no need for a unique solution, a further small change presents for 139 moves, with the king in check.

!> enter image description here

Addendum 8 Hours Later: Seeing as the OP agrees with the presented concept, but not the use of promoted material as per requirement #3, I shall provide the record without the use of them.

As it currently stands, again as of writing, the current length record for this task, however, without promoted pieces in a legal position, is a still astounding 129 moves.

Here is another direct link to it once more. This one is also verified to have one possible solution by a computer.

Branko Koludrovic, Cornel Pacura,, & Arno Tüngler, 496 mpk-Blätter 02/2012, 2. spezielle ehrende Erwähnung, Informalturnier 2012/13 Stipulation (The goal is to reach h2): ser-Zh2 in 129

enter image description here

Solution:

1. Bc1 2. Kd2 3. Kd3 4. Bd2 5. Be1 6. Kd2 7. Kc1 8. Kb1 9. Ka1 10. Bb1 11. Ka2 12. Ka3 13. Ka4 14. Ka5 15. Ka6 16. Kb7 17. Kc8 18. Kd7 19. Ke8 20. Kf7 21. Kg8 22. Kxh7 23. Kg6 24. Kh5 25. Kxg4 26. Kh5 27. Kg6 28. Kf7 29. Ke8 30. Kd7 31. Kc8 32. Kb7 33. Ka6 34. Ka5 35. Ka4 36. Ka3 37. Ka2 38. Ka1 39. Ba2 40. Kb1 41. Kc1 42. Kd2 43. Kd3 44. Bd2 45. Bc1 46. Kd2 47. Ke1 48. Kf1 49. Kxg1 50. Kf1 51. Ke1 52. Kd2 53. Kd3 54. Bd2 55. Be1 56. Kd2 57. Kc1 58. Kb1 59. Ka1 60. Bb1 61. Ka2 62. Ka3 63. Ka4 64. Ka5 65. Ka6 66. Kb7 67. Kc8 68. Kd7 69. Ke8 70. Kf7 71. Kg6 72. Kh5 73. Kg4 74. Kxh3 75. Kg4 76. Kh5 77. Kg6 78. Kf7 79. Ke8 80. Kd7 81. Kc8 82. Kb7 83. Ka6 84. Ka5 85. Ka4 86. Ka3 87. Ka2 88. Ka1 89. Ba2 90. Kb1 91. Kc1 92. Kd2 93. Kd3 94. Bd2 95. Bc1 96. Kd2 97. Ke1 98. Kf1 99. Kg1 100. Kxh1 101. Kg1 102. Kf1 103. Ke1 104. Kd2 105. Kd3 106. Bd2 107. Be1 108. Kd2 109. Kc1 110. Kb1 111. Ka1 112. Bb1 113. Ka2 114. Ka3 115. Ka4 116. Ka5 117. Ka6 118. Kb7 119. Kc8 120. Kd7 121. Ke8 122. Kf7 123. Kg6 124. Kh5 125. Kg4 126. Kxf3 127. Kg2 128. f4 129. Kh2

Again, since this is a legal position, and you allow for illegal ones, this is but a proven lower bound!

I have an answer that shall blow every other attempt here out of the water: 208 moves!

In essence, your requirements fulfill a genre of chess composition known as seriesmovers, which are problems in which only one side moves, with some exceptions on the very last move, and they can't be in check, minus the starting position, and cannot give a check, except on the last move in some of them.

A search of the Die Schwalbe Chess Problem Database reveals that the current record length, as of writing, to move a king to a designated square in a seriesmover in a legal position with promoted pieces, is 208 moves long.

Here is a direct link to it: moves there are in German notation. The nice thing is that this is a computer verified composition, meaning that there truly is only one possible solution,

The stipulation "ser-Ze3 in 208 moves" means this: The "ser" is short for seriesmover, the "-z" part is the accepted notation for problems in which the goal is for one side to reach a certain square, and, lastly, "e3" is the chosen target square.

Arno Tüngler, T140 ChessProblems.ca 13/05/2013, 1. Preis Stipulatiom: ser-Ze3 in 208

enter image description here

Lastly, here is the spoilered solution, but in English notation:

1. Kd1 2. Bf7 3. Bh5 4. Bg4 5. Bh3 6. Bf1 7. Bd3 8. Bc2 9. d3 10. Kd2 11. Kc3 12. Bb3 13. Kb4 14. Ka4 15. Bd1 16. Be2 17. Bf1 18. Bh3 19. Bg4 20. Bh5 21. Be8 22. Bd7 23. Bc8 24. Ba6 25. Bb5 26. Ka5 27. Ka6 28. Kb7 29. Kc8 30. Ba4 31. Bd1 32. Be2 33. Bf1 34. Bh3 35. Bg4 36. Bh5 37. Be8 38. Bd7 39. Kd8 40. Ke8 41. Bc8 42. Ba6 43. Bb5 44. Ba4 45. Bd1 46. Be2 47. Bf1 48. Bh3 49. Bg4 50. Bh5 51. Bf7 52. Kf8 53. Kg7 54. Bg6 55. Kh6 56. Kg5 57. Bh5 58. Bg4 59. Kh4 60. Kh3 61. Bh5 62. Be8 63. Bd7 64. Bc8 65. Ba6 66. Bb5 67. Ba4 68. Bc2 69. Kh2 70. Kxg1 71. Kh2 72. Kh3 73. Ba4 74. Bb5 75. Ba6 76. Bc8 77. Bd7 78. Be8 79. Bh5 80. Bg4 81. Kh4 82. Kg5 83. Bh5 84. Bg6 85. Kh6 86. Kg7 87. Bf7 88. Kf8 89. Ke8 90. Bh5 91. Bg4 92. Bh3 93. Bf1 94. Be2 95. Bd1 96. Ba4 97. Bb5 98. Ba6 99. Bc8 100. Bd7 101. Kd8 102. Kc8 103. Be8 104. Bh5 105. Bg4 106. Bh3 107. Bf1 108. Be2 109. Bd1 110. Ba4 111. Bb5 112. Kb7 113. Ka6 114. Ka5 115. Ka4 116. Bba6 117. Bc8 118. Bd7 119. Be8 120. Bh5 121. Bg4 122. Bh3 123. Bf1 124. Be2 125. Bd1 126. Bb3 127. Kb4 128. Kc3 129. Bc2 130. Kd2 131. Kc1 132. Bd1 133. Be2 134. Kd1 135. Kxe1 136. Kd1 137. Kc1 138. Bd1 139. Bc2 140. Kd2 141. Kc3 142. Bb3 143. Kb4 144. Ka4 145. Bd1 146. Be2 147. Bf1 148. Bh3 149. Bg4 150. Bh5 151. Be8 152. Bd7 153. Bc8 154. Ba6 155. Bb5 156. Ka5 157. Ka6 158. Kb7 159. Kc8 160. Ba4 161. Bd1 162. Be2 163. Bf1 164. Bh3 165. Bg4 166. Bh5 167. Be8 168. Bd7 169. Kd8 170. Ke8 171. Bc8 172. Ba6 173. Bb5 174. Ba4 175. Bd1 176. Be2 177. Bf1 178. Bh3 179. Bg4 180. Bh5 181. Bf7 182. Kf8 183. Kg7 184. Bg6 185. Kh6 186. Kg5 187. Bh5 188. Bg4 189. Kh4 190. Kh3 191. Bh5 192. Be8 193. Bd7 194. Bc8 195. Ba6 196. Bb5 197. Ba4 198. Bd1 199. Be2 200. Kg2 201. Kxf3 202. Kf2 203. Ke1 204. fxe6 205. Bd1 206. Bc2 207. Kd2 208. Ke3

Now, since this is a legal position, and you allow for illegal ones, this is merely a proven lower bound!

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  • 5
    $\begingroup$ This is crazy, definitely something fascinating. It had not occurred to me at all that checking the black king must be prevented; I do agree with that. I do feel however this violates the 3rd requirement: pawns promoted to rook are not starting material. $\endgroup$
    – Retudin
    Commented Nov 13, 2020 at 6:58
  • $\begingroup$ @Retudin Without promoted material is easily mended-will update soon. $\endgroup$
    – Rewan Demontay
    Commented Nov 13, 2020 at 12:02
  • $\begingroup$ @Retudin My answer has now been amended with a 129 move long record. $\endgroup$
    – Rewan Demontay
    Commented Nov 13, 2020 at 12:21
  • $\begingroup$ Well,I just upped my solution to 74; only 56 to go :-).Oh wait, success: 131 (your solution, with an extra pawn on a8, just to prove there are better 'illegal' ones) $\endgroup$
    – Retudin
    Commented Nov 13, 2020 at 14:35
  • $\begingroup$ What god does adding a pawn on a8 do? The White king never goes there. But I have some ideas with Black pawns. You'll see soon enough. :) $\endgroup$
    – Rewan Demontay
    Commented Nov 13, 2020 at 14:50
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I think I've got 25 steps - it's not brilliant but might be something to start with:

My setup looks like this:

T

White has only one piece (king) which starts on a1 (blue). The goal is to reach h1 (green).

I made an error with the image in that the knight on d8 should be on b8 and the pawn on e3 should be removed completely

The least amount of steps to get there appears to be:

Ka2, Ka3, Ka4, Ka5, Kxb6, Kc5, Kd6, Ke6, Kxf7, Kg8, Kxh8, Kxg7, Kxh6, Kxg5, Kxh4, Kh3, Kh2, Kg1, Kxf2, Kxg3, Kf4, Kxe4, Kf3, Kg2, Kh1, DONE!

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  • $\begingroup$ I can't get spoilers to work on the image. $\endgroup$
    – William Pennanti
    Commented Nov 10, 2020 at 17:03
  • $\begingroup$ Decent score, but 8 Ke6 is not allowed. OK you already noticed that.. $\endgroup$
    – Retudin
    Commented Nov 10, 2020 at 17:07
  • $\begingroup$ I do see Kg1 is also not allowed. $\endgroup$
    – Joel Rondeau
    Commented Nov 10, 2020 at 21:30
  • $\begingroup$ Ahh, yes. I can fix it, it will just take a couple more moves. I will do this soon. $\endgroup$
    – William Pennanti
    Commented Nov 11, 2020 at 7:50

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