No. 452 , Jan. 1997 - SOLUTIONS

630 - **A. Kornilov**

Europe Echecs 452, 01/1997

Bl. only cap. is fxQe. Wh. caps are axb, bxc, cxd & hxg. Right now, we can only retract moves by the Knights and 2 bl. retro-tempi: a4-a3 & c4-c3.

The position unlocks by extracting the bN via the g7-h5-g3 pathway and interposing it between the bKf4 and the wRc5 which will then be extracted through c4. The difficulty is that the corridor h7-f8-d7-b8-a6-c7-e8-g7-h5 is obstructed by the 2 wNs (who cannot go to h5) and there is only one side-square on a8 where the crossing can occur. This gives rise to a retro-opposition for which we need retro-tempi.

If we assume Bl. did move last, we get

-1. Nd7-f8 Ne8-c7

-2. Nb8-d7 Nc7-e8

-3. Na6-b8 Na8-c7

-4. Nc7-a6 Ne8-g8

-5. a4-a3 Ng7-e8

-6. Ne8-c7 Nc7-a8

-7. c4-c3 and the position will never open.

If we assume Wh. did move last, we need one less tempo-move and the
position unlocks easily. Hence **Bl. has the move** and Wh. cannot
mate in 1 with 1. Nxe6 #.

631 - **M. Caillaud**

Europe Echecs 452, 01/1997

Ded. Thierry Le Gleuher

1. a4 h5 2. Ra3 h4 3. Rg3 hxg3 4. d3 Rh4 5. Kd2 Rb4 6. h4 e5 7. h5 Qh4 8. h6 Qc4 9. h7 e4 10. Rh6 exd3 11. Rb6 axb6 12. h8=R Ra5 13. Rh1 Rh5 14. a5 Bc5 15. a6 d6 16. a7 Bg4 17. a8=R Bf3 18. Ra1 Ra4 19. gxf3 Ra8 20. f4 Qa6 21. Kc3 Rh8

632 - **S. Vokal**

Europe Echecs 452, 01/1997

(This problem was later found to be cooked)

Probably author's intention is to retract -1. e2xBf3 and prove that Bl. may not O-O-O in the resulting position, so that forward 1. Rxf3 and 2. Rf8# cannot be countered with 1 ... O-O-O

However, here is a proof game showing that Bl. O-O-O is still legal after we retract e2xBf3: 1. d4 Nc6 2. Qd3 Na5 3. Qg3 c6 4. Qc7 a6 5. Bf4 h6 6. Bd6 exd6 7. Qxc8 d5 8. Qc7 f5 9. Qb6 Bc5 10. dxc5 Qe7 11. Nf3 Qe3 12. fxe3 f4 13. Ne5 Nf6 14. Nc4 dxc4 15. Qb3 cxb3 16. Kf2 f3 17. Kg3 f2 18. Rg1 fxg1=Q 19. Kh4 Ne4 20. Kh5 Rf8 21. Kg6 Rf4 22. Kh7 Nd2 23. Kg8 Rb4 24. h3 bxa2 25. Kh8 axb1=B 26. Ra3 Qf2 27. Kg8 Qf4 28. Kh7 Qd4 29. exd4 Rb5 30. Rf3 Ba2 31. Rf2 Ndb3 32. d5 Nc1 33. d6 Bd5 34. Kh8 Be4 35. Kg8 Bf3 and now 36. exf3.

633 - **T. Volet**

Europe Echecs 452, 01/1997

Ded. Philippe Schnoebelen

Bl. caps are cxd, hxg and wQb at home, so that bPf2 is from f7 with no capture. bPa7 did promote on a1 for balance. Wh. caps are g2xf3, f6xe7 & axb.

The position unlocks by reconducting the wKB on f1 but this needs a complex interposition play:

-1. c6xBd5 Bc4-d5

-2. c7-c6 Ba6-c4

-3. Ra8-b8 Bb5-a6

-4. Rb8-a8+ Ba4-b5

-5. Ra8-b8 h5-h6

-6. Ra6-a8 Bb5-a4

-7. Rd6-a6+ Bc4-b5

-8. Rd4-d6 Bd5-c4

-9. Rd3-d4 Be4-d5

-10. g6-g5 Bf5-e4

-11. Rd5-d3 Bh3-f5+

-12. R~ Bf1-h3

-13. R~ g2xN/Q/..f3

-14. N/...-f3 h4-h5

-15. f3-f2 Nf2-d1 and everything unlocks.

The wKB necessarily visited f1, h3, f5, e4, a4, b5, a6, d5 & c4 ! Square a6 cannot be avoided because retracting h7xg6 for one more bl. tempo would lock the wRs inside the North cage.