Let's book a look and figure out the rooks from the mooks.
Which ones are the original kings' rooks?
This was composed by Boris M. Klementjew and published in Shakhmatnaya Kompozitsiya 15, page 60, 1992, earning second prize.
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asked May 30, 2023 at 4:20
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1 Answer
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Answer:
Only the rook on e7. The two white rooks are promoted pawns.
Constraints:
Black pawns h5 and h2 must have come from f7 and c7 (7 black captures) Bc8 must have been captured (1 white capture) That leaves only pawn a2 to have become Be8 on b1 (1 black capture) No other black piece can be promoted
As soon as the Be8 and Kg6 are in position f7 must plugged before each black move (meaning that white pieces can't get through and black pieces only by capturing on f7 -> 2 black captures 1 for each rook) Be8 and Kg6 must have moved there before e7-e6 (the king entering via the 8th rank or from g5 directly after h7-h6+ can be ruled out) In particular, white pieces in the top right corner could only have got there before or via promotion d6xe7xf8 (min 2 white captures -> can have happened at most once) Therefore Rh7 and Nh8 must have entered before their king. At that time Bf8 can't have moved and Rh8 no further than to g8. As both are untouchable the white rook must be pawn b2 promoted (1 white capture) In the final position the double checking rook cannot have come from f8 (ie Rf8xf7 ... Rf7-f6#) because there would be no possible white move in between (no white piece could have moved to f6 because all missing white pieces are accounted for)
Proof game (not optimised, I'm sure this could be shortened):
1. g4 a5 2. Nc3 h6 3. g5 Nf6 4. g6 Nh7 5. gxh7 Rg8 6. h8=R a4 7. Nd5 a3 8. Nb6 axb2 9. Nxc8 b1=B 10. a4 Ba2 11. e4 Nc6 12. Nd6+ cxd6 13. e5 dxe5 14. Bd3 Qb6 15. Qh5 Kd8 16. Ke2 Kc7 17. Kf3 Kd6 18. Nh3 Kd5 19. Nf4+ Kd4 20. Ng6 Ra6 21. Rh7 Qb5 22. Nh8 Qb6 23. Bg6 fxg6 24. c4 gxh5 25. c5 Kd3 26. Rb1 Kc2 27. d4 Bf7 28. Ke4 Be8 29. Rb3 Qb5 30. Rf3 Qb6 31. Rf7 Qb5 32. Kf5 Kd3 33. d5 Rb6 34. d6 e6+ 35. Kg6 Be7 36. h3 Bh4 37. Rg1 Bg3 38. Bf4 exf4 39. a5 Nb4 40. a6 Nd5 41. a7 Nf6 42. a8=Q Rf8 43. c6 Ng8 44. c7 Qa5 45. c8=Q Rb3 46. Qc3+ Ke2 47. Rh1 Bh2 48. Qg3 Bg1 49. Rh2 fxg3 50. Qc8 gxh2 51. Qc5 Qd8 52. Qf5 Qe7 53. Qf4 Kf1 54. Qf5 Rxf7 55. Qf4 Qf8 56. Qf5 Ne7+ 57. dxe7 Kg2 58. exf8=R Rf3 59. Qf4 Re7+ 60. Qf7 Rfxf7 61. Rg8 Rf6#
