The Retrograde Analysis Corner
No. 100, Oct. 2000 - SOLUTIONS
8273 - Henrik Juel
With 20 bishops, all pawns were promoted, and there are 8 white bishops and 6 black bishops on light squares, an imbalance of 2. So all missing men were captured by pawns, 8 necessary to enable the promotions and 2 extra to create the imbalance. Last move was not c2xb1=B+ or c2xd1=B+, because these would be extra captures, but they would change the balance in the wrong direction. So last move was b2-b1=B+.
8274 - Gianni Donati
1. e3 g5 2. Qe2 Bh6 3. Qa6 ba6 4. b4 Bb7 5. b5 Bd5 6. b6 Nc6 7. b7 Rc8 8. b8=Q Bc4 9. Qb6 Nb8 10. Qg6 c6 11. Bb2 Qc7 12. Bg7 Qf4 13. ef4 gf4 14. Bf8 Bg5 15. Qg8 Bh4 16. Qg4 Rg8 17. Qd1 Rg3 18. Bg7 Rd3 19. Bb2 f3 20. Bc1
8275 - Unto Heinonen
1. a4 h5 2. a5 h4 3. Ra4 h3 4. Na3 hg2 5. h4 d5 6. h5 d4 7. h6 d3 8. h7 de2 9. d4 g5 10. d5 g4 11. Bh6 g3 12. Rg4 e5 13. f4 e4 14. Nf3 g1=R 15. Rh5 g2 16. Kf2 e1=R 17. Bc4 Re3 18. Ba2 Rb3 19. Qd3 Rc1 20. cb3 Rc6 21. Nc2 Ba3 22. Bf8 g1=R 23. Rg7 Rg5 24. fg5 e3 25. Kg3 e2 26. dc6 e1=R 27. cb7 Re4 28. Nce1 Ra4 29. ba4
But Juris Grudulis found the following cook: 1. a4 g5 2. a5 g4 3. Ra4 g3 4. Rg4 e5 5. d4 Bc5 6. dc5 h5 7. Bh6 h4 8. Bf8 h3 9. f4 hg2 10. Nf3 g1=B 11. c6 Bc5 12. Rg7 g2 13. cb7 g1=R 14. Na3 Rg5 15. fg5 d5 16. h4 d4 17. Kf2 d3 18. Kg3 de2 19. h5 e1=R 20. Bc4 Re3 21. Ba2 Rb3 22. cb3 e4 23. Nc2 e3 24. h6 e2 25. h7 e1=R 26. Qd3 Re4 27. Rh6 Ra4 28. ba4 Ba3 29. Nce1
8290 - Nikita Plaksin
If White had the move, there would be 25 solutions. But Black has no previous move, so he has the move, with one solution: 1.. h1=Q#
8291 - Satoshi Hashimoto
1. b4 g5 2. Bb2 Bh6 3. Bf6 ef6 4. b5 f5 5. b6 Nf6 6. bc7 00 7. cb8=N Qc7 8. Nd7 Qb8 9. Nb6 ab6
8292 - Mark Kirtley
1. g4 Nf6 2. g5 Nd5 3. g6 hg6 4. Nc3 Rh5 5. Ne4 Re5 6. c3 f5 7. Qa4 Kf7 8. Qd7 Qe8 9. Qc7 Ke6 10. Qb6 ab6 11. f3 b5 12. Nf2 Nb6