May-June 2006

R307 - Andrei Frolkin, Kostas Prentos

Probleemblad May-June 200

1. e4 f6 2. Ba6 bxa6 3. Qg4 Bb7 4. Qg6+ hxg6 5. e5 Rh3 6. e6 Rf3 7. exd7+ Kf7 8. d4 e5 9. d5 e4 10. d6 e3 11. dxc7 Be4 12. c8=B Qb6 13. d8=Q Nc6 14. Qd1 Bd6 15. Bh3 Nge7 16. g4 Rh8 17. Bf1 Rh5 18. gxh5 e2 19. Bh6 g5 20. Kd2 e1=N 21. Be2 Nd3 22. Qf1 Ng6 23. Bd1

Two Pronkin pieces switch places.

R308 - Unto Heinonen

Probleemblad May-June 2006

1. d4 h5 2. Bh6 f5 3. Kd2 Kf7 4. Ke3 Ke6 5. Kf4 Kd5 6. Kg5 Ke4 7. f3+ Ke3 8. Kg6+ Kf2 9. Kf7 g5 10. a4 Bg7 11. Ra3 Bxd4 12. Bf8 Be3 13. Qd6 Rh6 14. Qxc7 Rd6 15. Rc3 Rd1 16. Na3 Ra1 17. Rc6 Bc1 18. e3 Ke1 19. Ba6 b5 20. Rh6 Bb7 21. Rh8 Be4 22. Bc8 Bd3 23. Nh3+ Bf1 24. Nf4 Na6 25. Ne6 Rb8 26. Ng7 e6 27. Rg1 Qf6+ 28. Ke8 Qd4 29. Qd8 Qd1

Five officers (including kings) exchange place.

R309 - Guus Rol

Probleemblad May-June 2006

Dedicated to R.J. Aumann and T.C. Schelling

Composer's solution: The solution shows the battle between castling right and the strategic threat of an automatic repetition draw. 1. Bg8 Se6 2. Bh7! Sf8 3. Bg8! Se6 At this point black has lost the right to castle as a retro-strategic consequence of the single white repetition plus the retro-analysis of the diagram position. If black still had castling rights, then the last two moves could only have been Ne6-f8 and Bg8-h7, or in other words, the position after move 3 would be drawn. However, no position may be considered drawn unless double repetition is absolutely certain. Such not being the case, we are forced to play on at the expense of the black castling right. 4. Qf1! Another way to look at it is by considering the black defense OOO at this point. Analysis shows that any proofgame must contain a "premature" double repetition and is therefore an illegal game. Hence, OOO is illegal. 4... Ng5 5. Kg2 h3 6. Kh1 Nf3/Ne6 7. Bh7/Bf7#.

R310 - Vlaicu Crisan, Klaus Wenda

Probleemblad May-June 200

-1. Bg7-h8! Bg1-h2 -2. Kf2xPg2[Ke1] Bh2-g1 -3. Ke1-f2 Bg1-h2 -4. Ke2xPd2[Ke1] f4-f3 -5. Kf2-e2 Bh2-g1 -6. Kg3-f2 Bg1-h2 -7. Bh8-g7 f5-f4 -8. Kf2-g3 Bh2-g1 -9. Ke1-f2 d3-d2 -10. h7-h8=B Bg1-h2 -11. Kh4xBh5[Ke1] Bh2-g1 (h2-h1=R? illegal) -12. Kg3-h4 Bg1-h2 -13. Kf2-g3 Bh2-g1 -14. Ke1-f2 Bg1-h2 -15. Kg8xQh8 Qf6-h8 -16. Bf4-e5 and 1. h8=N Qh8[Qd8]#

The main plan is -1. h7-h8=B? Bg1-h2 -2. Kg8xQh8 Qf6-h8 -3. Bf4-e5 and 1. h8=N Qh8[Qd8]#, but this fails due to the flights f5 and h5. With the plan -2. Kh4xBh5[Ke1] Bh2-g1 -3. Kg3-h4 Bg1-h2 -4. Kf2-g3 Bh2-g1 -5. Ke1-f2 Bg1-h2, h5 is blocked but f5 is still a flight. In a second foreplan, the black pawn on f3 must be forced back to f5. For this to succeed, white first blocks g7 and then the white king uncaptures a black pawn on g2 to avoid the refutation -3...g2-g1=B.