sexta-feira, 3 de novembro de 2017

Xadrez - Mate em 203! (Walther Jørgensen; André Chéron)

Walther Jørgensen, Die Schwalbe, 1976 (ligeiramente modificado por André Chéron).
Código FEN: 6n1/p1BN3b/p1p3np/p1p2rpq/6kr/K1P4p/2PP4/7Q w - - 0 1.

As Brancas jogam e dão xeque-mate em 203 lances! Até hoje, este é o mais longo problema de mate direto sem duais e sem promoções de peões já composto.

(White to play and give checkmate in 203 moves! Until today, this is the longest dual-free direct mate problem without pawn promotions ever composed.)

PCFilho
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11 comentários:

  1. Unknown4 de novembro de 2017 às 16:48

    Mate in 203? Is that even possible? 😂

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  2. jrh1504825 de novembro de 2017 às 20:52

    I tried having Stockfish solve this, and the best it could come up with was a draw by perpetual check.

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    Respostas
    1. PC Filho6 de novembro de 2017 às 05:56

      Yes, Jake! I tested some softwares too, and they all failed miserably. :)

      That is because of the so-called "horizon effect": the number of possible continuations is immensely huge, and computers cannot feasibly search them all. :)

      However, it is possible to use engines in a clever way, in order to help finding the solution. That is what I did.

      Tomorrow, I will post the solution, explaining it step by step. :)

      Excluir
    2. Unknown7 de novembro de 2017 às 19:56

      I have a feeling that we have to blockade the h3-Pawn by placing the Bishop on h2. This would "lock" almost all Black pieces, and so White would be able to maneuver his pieces.

      However, 1. Bh2? does not work. I guess White needs to "prepare" this move first. He has to find a way of "locking" the f5-Rook before playing Bh2. How to do this?

      Excluir
  3. PC Filho11 de novembro de 2017 às 18:42

    The first step of the solution is to blockade the Black Pawn on h3. This is done in 5 moves:
    1. Qg1+!! Kf3 2. Qf1+! (2. ... Ke4 3. Qd3#)
    2. ... Kg4 3. Qe2+ Rf3 4. Qe6+ Rf5 5. Bh2!!

    Black cannot move the g6-Knight, because of 5. ... Nf8 6. Ne5#
    The g8-Knight cannot move either, because of:
    5. ... N8e7 6. Qe2+ Rf3 7. Qe4+ Rf4/Nf4 8. Nf6#
    5. ... Nf6 6. Nxf6+ Kf3 7. Qe3+ Kg2 8. Qg1+ Kf3 9. Qf1#
    So, no Black pieces can be moved, except for the King.
    5. ... Kf3 6. Qe3+! (6. ... Kg4 7. Qg3#)
    6. ... Kg2 7. Qg1+ Kf3 8. Qf1+! (8. ... Ke4 9. Qd3#)
    8. ... Kg4 9. Qe2+ Rf3 10. Qe6+ Rf5

    Now we're back to the same position we had after 5. Bh2!!, but with White to move. These last 5 moves are the so-called Jørgensen Maneuver (6. Qe3+ Kg2 7. Qg1+ Kf3 8. Qf1+ Kg4 9. Qe2+ Rf3 10. Qe6+ Rf5).

    Now, if the Black pawns on the a and c-files didn't exist, the game would soon be over: White would play the Jørgensen Maneuver 3 times, bringing his King to d1, after which Black would not be able to play ... Kf3 anymore, because of Qe2#. Then, he would have to move a Knight, leading to checkmate, as described above.
    However, it is not as simple as taking all the Pawns. In order to keep the Black pieces tied up, White has to be much more careful...

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    Respostas
    1. PC Filho11 de novembro de 2017 às 18:43

      11. Kb2!! Kf3 12. Qe3+ Kg2 13. Qg1+ Kf3 14. Qf1+ Kg4 15. Qe2+ Rf3 16. Qe6+ Rf5 17. Kc1 Kf3 18. Qe3+ Kg2 19. Qg1+ Kf3 20. Qf1+ Kg4 21. Qe2+ Rf3 22. Qe6+ Rf5 23. Kd1!!

      Now, Black has to move a Pawn, because of 23. ... Kf3 24. Qe2#
      23. ... a4 24. Kc1!! (24. Ke1? would allow the promotion of the a4-Pawn, losing the game.)

      And here we go with the Jørgensen Maneuver again...
      24. ... Kf3 25. Qe3+ Kg2 26. Qg1+ Kf3 27. Qf1+ Kg4 28. Qe2+ Rf3 29. Qe6+ Rf5 30. Kd1!!

      Black's best move now is 30. ... a5. (After 30. ... a3? 31. Kc1 ... 37. Kb1 ... 43. Ka2 ... 49. Kxa3 ... 55. Kb2 ... 61. Kc1, White would play three King moves without the Jørgensen Maneuver (67. Kd1 a5 68. Ke1! a4 69. Kd1!), "saving" 10 moves.

      Once more, the Jørgensen Maneuver to force another Pawn to move...
      31. Kc1!! Kf3 32. Qe3+ Kg2 33. Qg1+ Kf3 34. Qf1+ Kg4 35. Qe2+ Rf3 36. Qe6+ Rf5 37. Kd1!!

      And here we go again, the Jørgensen Maneuver to force another Pawn to move...
      37. ... a6 38. Kc1!! Kf3 39. Qe3+ Kg2 40. Qg1+ Kf3 41. Qf1+ Kg4 42. Qe2+ Rf3 43. Qe6+ Rf5 44. Kd1!!

      Now Black has to move the Pawn to a3, where it will be finally captured, after four Jørgensen Maneuvers...
      44. ... a3 45. Kc1!! Kf3 46. Qe3+ Kg2 47. Qg1+ Kf3 48. Qf1+ Kg4 49. Qe2+ Rf3 50. Qe6+ Rf5 51. Kb1!! Kf3 52. Qe3+ Kg2 53. Qg1+ Kf3 54. Qf1+ Kg4 55. Qe2+ Rf3 56. Qe6+ Rf5 57. Ka2!! Kf3 58. Qe3+ Kg2 59. Qg1+ Kf3 60. Qf1+ Kg4 61. Qe2+ Rf3 62. Qe6+ Rf5 63. Kxa3!!

      Excluir
    2. PC Filho11 de novembro de 2017 às 18:44

      Now, the White King will return to d1, forcing Black to move another Pawn. Some more Jørgensen Maneuvers are necessary, of course:
      63. ... Kf3 64. Qe3+ Kg2 65. Qg1+ Kf3 66. Qf1+ Kg4 67. Qe2+ Rf3 68. Qe6+ Rf5 69. Kb2 Kf3 70. Qe3+ Kg2 71. Qg1+ Kf3 72. Qf1+ Kg4 73. Qe2+ Rf3 74. Qe6+ Rf5 75. Kc1 Kf3 76. Qe3+ Kg2 77. Qg1+ Kf3 78. Qf1+ Kg4 79. Qe2+ Rf3 80. Qe6+ Rf5 81. Kd1!! a4

      Now, White will move his King between c1 and d1, always using the Jørgensen Maneuver, forcing Black to play some more Pawn moves:
      82. Kc1 Kf3 83. Qe3+ Kg2 84. Qg1+ Kf3 85. Qf1+ Kg4 86. Qe2+ Rf3 87. Qe6+ Rf5 88. Kd1 a5 89. Kc1 Kf3 90. Qe3+ Kg2 91. Qg1+ Kf3 92. Qf1+ Kg4 93. Qe2+ Rf3 94. Qe6+ Rf5 95. Kd1 c4 96. Kc1 Kf3 97. Qe3+ Kg2 98. Qg1+ Kf3 99. Qf1+!

      Now, the White Queen cannot move to d3, so Black could try 99. ... Ke4. However, it doesn't work, because of 100. d3+!! Ke3 101. Bg1+ Rf2 102. Qxf2# (100. ... Kd5 101. Qxf5+ Ne5 102. Qxe5#)

      So, we continue with the Jørgensen Maneuver:
      99. ... Kg4 100. Qe2+ Rf3 101. Qe6+ Rf5 102. Kd1!! c5 103. Kc1 Kf3 104. Qe3+ Kg2 105. Qg1+ Kf3 106. Qf1+!

      And now? With the free c6-square, can Black play 106. ... Ke4 and escape? No, because of: 107. d3+!! Kd5 (107. ... Ke3 108. Bg1+ Rf2 109. Qxf2#) 108. Qxf5+ Kc6 109. Qe6+ Kb7 (109. ... Kb5 110. Qb6#) 110. Qb6+ Ka8 (110. ... Kc8 111. Qc7#) 111. Qb8#

      So, Black is forced to keep following the Jørgensen Maneuver...
      106. ... Kg4 107. Qe2+ Rf3 108. Qe6+ Rf5 109. Kd1!!

      109. Kb2?, going for the a4-Pawn, wouldn't work. Now Black is forced to advance the Pawn to a3...
      109. ... a3 110. Kc1! Kf3 111. Qe3+ Kg2 112. Qg1+ Kf3 113. Qf1+ Kg4 114. Qe2+ Rf3 115. Qe6+ Rf5 116. Kb1! Kf3 117. Qe3+ Kg2 118. Qg1+ Kf3 119. Qf1+ Ke4!

      Now this is the best move for Black, temporarily delaying the Jørgensen Maneuver. White's best continuation is...
      120. Qxc4+!! Kf3 121. Qf1+ Kg4 122. Qe2+ Rf3 123. Qe6+ Rf5 124. Ka2!!

      One more Jørgensen Maneuver to capture the second Pawn on a3...
      124. ... Kf3 125. Qe3+ Kg2 126. Qg1+ Kf3 127. Qf1+ Kg4 128. Qe2+ Rf3 129. Qe6+ Rf5 130. Kxa3!!

      Excluir
    3. PC Filho11 de novembro de 2017 às 18:45

      And now the King heads back to d1, in order to force another Pawn to advance...
      130. ... Kf3 131. Qe3+ Kg2 132. Qg1+ Kf3 133. Qf1+ Kg4 134. Qe2+ Rf3 135. Qe6+ Rf5 136. Kb2! Kf3 137. Qe3+ Kg2 138. Qg1+ Kf3 139. Qf1+ Kg4 140. Qe2+ Rf3 141. Qe6+ Rf5 142. Kc1! Kf3 143. Qe3+ Kg2 144. Qg1+ Kf3 145. Qf1+ Kg4 146. Qe2+ Rf3 147. Qe6+ Rf5 148. Kd1!! a4

      And now we execute the Jørgensen Maneuver again, to force another Black Pawn to advance...
      149. Kc1! Kf3 150. Qe3+ Kg2 151. Qg1+ Kf3 152. Qf1+ Kg4 153. Qe2+ Rf3 154. Qe6+ Rf5 155. Kd1!! c4

      Once more...
      156. Kc1! Kf3 157. Qe3+ Kg2 158. Qg1+ Kf3 159. Qf1+!
      If Black tries to escape with 159. ... Ke4, the game ends with 160. d3+!! Kd5 161. Qxf5+ Kc6 162. Qe6+ Kb7 163. Qb6+ Ka8 164. Qb8#

      So, we follow with the Jørgensen Maneuver:
      159. ... Kg4 160. Qe2+ Rf3 161. Qe6+ Rf5 162. Kd1!! a3
      The third and last a-Pawn finally arrives on the a3-square, where it will be captured, as his first two brothers were...
      163. Kc1!! Kf3 164. Qe3+ Kg2 165. Qg1+ Kf3 166. Qf1+!
      Again, Black cannot escape with 166. ... Ke4, because of 167. d3+!! Kd5 168. Qxf5+ Kc6 169. Qe6+ Kb5 170. Qb6+ Ka4 171. Qb4# (169. ... Kb7 170. Qb6+ Kc8 171. Qc7#)

      So, we follow with the Jørgensen Maneuver again and again, until capturing the a3-Pawn:
      166. ... Kg4 167. Qe2+ Rf3 168. Qe6+ Rf5 169. Kb1!! Kf3 170. Qe3+ Kg2 171. Qg1+ Kf3 172. Qf1+ Kg4 173. Qe2+ Rf3 174. Qe6+ Rf5 175. Ka2!! Kf3 176. Qe3+ Kg2 177. Qg1+ Kf3 178. Qf1+ Kg4 179. Qe2+ Rf3 180. Qe6+ Rf5 181. Kxa3!!

      Excluir
    4. PC Filho11 de novembro de 2017 às 18:46

      Now the White King will begin to head again to the d1-square...
      181. ... Kf3 182. Qe3+ Kg2 183. Qg1+ Kf3 184. Qf1+ Kg4 185. Qe2+ Rf3 186. Qe6+ Rf5 187. Kb2!!

      In the next Jørgensen Maneuver, Black will delay the solution by moving the King to e4...
      187. ... Kf3 188. Qe3+ Kg2 189. Qg1+ Kf3 190. Qf1+ Ke4!
      However, two moves later, the Jørgensen Maneuver will be back:
      191. Qxc4+!! Kf3 192. Qf1+ Kg4 193. Qe2+ Rf3 194. Qe6+ Rf5 195. Kc1!!

      And finally, the last Jørgensen Maneuver, and the King arrives to the d1-square...
      195. ... Kf3 196. Qe3+ Kg2 197. Qg1+ Kf3 198. Qf1+ Kg4 199. Qe2+ Rf3 200. Qe6+ Rf5 201. Kd1!!

      Now, it's zugzwang! Whatever Black does, the game is over:
      201. ... Kf3 202. Qe2#
      201. ... Nh8/Nf8/N6e7/Ne5/Nf4 202. N(x)e5#
      201. ... N8e7 202. Nf6+!! Kf3 203. Qe2#
      201. ... Nf6 202. Nxf6+!! Kf3 203. Qe2#

      Excluir
    5. PC Filho11 de novembro de 2017 às 18:49

      That's it. Following and understanding each step might take you a couple of hours, but I really enjoyed writing it, and I think it's worth the effort. :)

      Excluir

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