Masterworks of Retro Analysis

by Karl Fabel - Solutions

L. Ceriani
Die Schwalbe, 1969


13+12. Release the position!

Analysis: Three wh. caps are hxg, the bQR in the NW corner, & the bKB at home. One bl. cap. (at least) is required by bPb2.

The only way to unlock the South cage is to move the bK to c1. But this needs interposing something on b1, between wQa1 and bKc1. Which unit can we bring back to b1? Nothing can go there from outside the cage ... After some time, we see that the only possibility is to uncapture on c1 something that can go to b1. But only a bl. Queen will do, and only a wh. Knight can reach c1 and uncapture a bQ there. Now is all this possible?

We need a wh. Knight. It can be uncaptured by Black. But retracting e.g. -1. h4xPg5 h6xNg5 will fail because Bl. has not enough waiting moves. We can get bl. retro moves by uncapturing the bQR but the uncaptured wNg5 needs too much time to reach a8 or b8. The trick is that we can first quickly uncapture the bQR and only then let it uncapture our wN !

Here is the way: retract
-1. g4-g5 f6-f5
-2. g3-g4 f7-f6
-3. h2xPg3 h4xBg3
-4. Bb8-g3 h5-h4
-5. Be5xRb8 Ra8xNb8
-6. Na6-b8 R~
-7. Nc5-a6 R~
-8. Nd3-c5 R~
-9. Nc1-d3 R~
-10. Nd3xQc1 Qb1-c1
-11. Nc5-d3 Kc1-c2
and now the position unlocks e.g. with -12. c2-c3.

This problem is the last brain-twister L. Ceriani submitted to the aspirin addicts from Die Schwalbe. It displays very fine uncaptures of Q/R/B/N/P. All are completely determined (except the a8/b8 ambiguity for the N).