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No. 113, Apr. 1995 - SOLUTIONS

3298 - Andrey Kisliak

(as posted by Richard Sabey to the retro-list) The last move was g3 by White. Therefore White's bishop from f1 was captured on f1 by a piece. So WBh5 is promoted, and White's h-pawn promoted to WB on g8. Only one WP is missing, so (in particular) WNg8 is original.

If Black played gxf6 before h6, then he played Bh8 and White played g7 and g8=B, but this requires the following sequence, which is impossible: Nh6-g8; ...h6; Bg8-h7.

Therefore Black played h6 before gxf6, so White has played Nf6, then Nf6-g8. Therefore the following sequence happened:

hxg and ...h6
gxh7
hxg8=B
Bh7 (and eventually Bh5)
Nf6-g8
...gxf6
...Bg7
...Bh8

Therefore BBh8 has always been confined to f8, g7, h8. So it is original. (Another way to see that is this: an argument below will prove that Black's only promotion happened on b1; but that is a white square, and we need a black-squared bishop; and anyway the promoted bishop would be confined to b1 and a2.)

The BK must have moved before White played Nf6-g8. But at that time, Black had not yet played gxf6, so Black's f8 bishop hadn't yet moved. BBh8 is the original bishop from f8 (see above), so the BQ was captured before it ever moved, then Black played Ke8-d8, allowing White to play Nf6, then Nf6-g8.

So BQe8 is the promoted a-pawn. Of Black's 3 captures, one was gxf6, one was of the WBf1, leaving 1. So the black a-pawn reached a2. So the following sequence happened:

Na1
axb3
...a2
...axb1=Q
...Qa2

...axb1=Q accounts for all 3 black captures. So ...Qa2 was not a capture.

Answer: Qb1-a2.

(You could be devious: if you mean the original black queen, off the board and back into the box when it got captured; if you mean BQe8, out of the box and onto b1 when it got created by a promotion.)


3299 - Andrey Frolkin

1. h4 Nc6 2. h5 Ne5 3. h6 Ng4 4. hxg7 h5 5. f4 h4 6. f5 h3 7. f6 Rh4 8. fxe7 N8h6 9. g8=B Bg7 10. Bxf7 Kxf7 11. e8=R Qf6 12. e3 Qa6 13. Re6 Be5 14. Rc6 bxc6 15. Bc4 Kg6 16. Ne2 Bb7 17. O-O Rg8 18. Rf8 Rg7 19. Bg8 Nf7 20. Re8 h2

Anti-phoenix theme. Two men (here wR + wB) on promotion squares really are the original men.


3300 - Thierry Le Gleuher

Last move is g4xh5+

bNg1 and b1 have been promoted, using all 8 captures of missing wh. units.

bRa8 and bNg8 captured on home squares, wRf4 is a promotee, requiring 4 captures of bl. units: bQ, bKB, dark-squared bP, light-squared bP en passant.

bPd7 went d7-d5 x Pc4 x Pb3ep x Pa2 x Nb1=N.
bPc7 went c7-c5 x Pd4 x e3 x Pf2 x Ng1=N.
wPh2 went h2-h4 x g5 x h6ep x g7 x f/h8=R.

bQB was captured on h5. Once g4xBh5+ is retracted, the Bl. position unlocks by retracting g2-g4. But we have to drive the wBf1 back home before. A few tempi can be given to save Bl. from retro-stalemate by driving the wRa1 (uncaptured on e3) back home, so that bPa2xb1 can be retracted. The quickest (and only possible) way is:

-1. g4xBh5+ f2xNg1=N -2. Kd4-e3 e3xPf2 -3. Ke5-d4 d4xRe3 -4. Ra3-e3 c5xPd4 -5. Bc3-a1 c7-c5 -6. Ra1-a3 a2xNb1=N -7. Bd5-e6 b3xPa2 -8. Bg2-d5 c4xPb3ep -9. b2-b4 d5xPc4 -10. Qd1-f1 d7-d5 -11. Bf1-g2 Kf5-g6 -12. g2-g4+ and everything unlocks. (Bl. did O-O).

Last 23 moves precisely determined !!