[Retros] Puzzle - Pronkin-knight

[per olin]

Dear retro friends,

A couple of weeks ago Nicolas Dupont wrote
Qoute:   Construct a Knight Pronkin (during a PG an original Knight is captured and replaced on its homesquare by a promoted one) with 28 homebased pieces in the diagram position.  In my dreams the solution is also unique!   Unquote

Having given this some attention, my best effort is an unique solution with 27 homebased pieces:  (French notation by Euclide) 1. Cg1-f3  Pa7-a5  2. Cf3-d4  Pa5-a4  3. Cd4-b3  Pa4xb3   4. Pa2-a4 Ta8-a6  5. Pa4-a5 Ta6-b6   6. Pa5-a6 Pc7-c6 7. Pa6-a7  Tb6-a6  8. Pa7-a8=C Dd8-a5   9. Ca8-b6  Re8-d8   10. Cb6-c4  Rd8-c7   11. Cc4-e5   Rc7-d6  12. Ce5-f3 Da5-d8  13. Cf3-g1. My guess is that the dream with 28 homebased pieces will continue to be a be a dream


The target of 28 pieces can be reached when starting from another Chess960 initial position (Chess960IP).   From Chess960IP a-h TSLDKLTS the Pronkin-knight theme needs 9.5 moves: 1.Sh1-g3 g7-g6  2.Sg3-f5 g6*f5   3.g2-g4 Tg8-g6   4.g4-g5 Tg6-b6   5.g5-g6 f5-f4   6.g6-g7 f4-f3   7.g7-g8=S Lf8-g7   8.Sg8-h6 Lg7-c3   9.Sh6-f5 Lc3-a5  10.Sf5-g3 Tb6-b4  11.Sg3-h1 a=>b.

Computer tests:   for the first one,  Euclide needs 2.50 seconds to verify the unique solution.  For the latter one, test performed with the Chess960IP as position A and the position to reach as position B.  The a=>b-function of Popeye needs, for reasons I don't have knowledge about, almost 11 hours to make the full test (without constraints).  -  Popeye is a wonderful freeware for which we are grateful.  When, as we hope, Popeye is developed further and improved, we will be even more grateful.

Best wishes
Per