The Retrograde Analysis Corner
No. 123 , Oct. 1997 - SOLUTIONS
3870 - N. Plaksin and A. Zolotarev
(Mate in one is with 1. de5 Nxe7/Rd8/xe7. But this is not the interesting part.)
Wh. caps are gxfxe7, exd and b2x3. For balance, Bl. had to promote his 4 missing Pawns, which required the captures axb and hxg. Posiiton unlocks by retract b2xc3. This requires the earlier unpromotions of bPa7 and bPb7 on b1, and the reconduction of wBc1 that has to be uncaptured by hxg.
Retract:
-1. Nf3-e5+ f6xQe7
-2. Ng3-f1 f5-f6
-3. g2-g1=N e3xRd4
-4. g3-g2 e2-e3
-5. h4xBg3 and White's retropat is avoided.
Further unlocking requires:
(1) reconduct wBg3 on b1,
(2) unpromote bQe7 on g1,
(3) reconduct bPg past g5,
(4) retract g4xRf5,
(5) unpromote bRf5 and bRd4 on b1,
(6) retract b2xNc3 and the position unlocks.
Triple Ceriani-Frolkin theme with precise capture squares.
3871 - Thierry Le Gleuher
All missing wh. units have been captured by the bl. Pawns. The wh. Pawns captured axbxa and dxexfxgxh. Thus White cannot retract h2-h4 or h3-h4 (wKR must get out) or g3xh4 (excess of captures). Hence White's only possible retraction is g6xh7 and we cannot play 1. Kf7.
1. c5 2. c4 3. c3 4. c2 5. c1=N! and now 6. Kf7 is allowed. Play goes on with 7. Kg6 8. Kh5 9. Kxh4 10. h5 g3#
3872 - Christian Poisson
a) 1. c3 e6 2. Qa4 Bc5 3. Qd7 Kf8(+bPe7) 4. Qe6 Bb6(+bPd7)
b) 1. c3 e6 2. Qb3 Bc5 3. Qe6 Kf8(+bPf6) 4. Qf6 Bb6(+bPe7) 5.
Qe6
3873 - Stanislav Vokal
White's queen, queen rook, and queen bishop were captured in the a1-d1 cage. So on h6 was either the the missing white pawn (which promoted and then got captured), or a knight captured (and in the last case the white pawn promoted to knight on g8). The piece captured on h3 must've been the missing rook. So the f-pawn captured the f8-bishop on its way to promotion, so g7xh6 must've happened before white promoted. So an original knight was captured on h6, and white promoted to a new knight on g8. This knight must've left g8 via f6, so the black king had to move. So black may not castle!
3874 - Jean-Michel Trillon
Neutral moves are bold:
1. e4 c4 2. e5 c5 3. Kb5 a6 4. Kb6 e4 5. Kc6 Ka7 6. e5 Ka8 7. e6 Ka7 8. e7 Ka8 9. a7 e6 10. Kb5 e5 11. Ka6 e4 12. c6 e3 13. c5
3875 - Didier Innocenti and Maryan Kerhuel