[Retros] Type D, new length record

[Mario Richter]

Dear retro fans,

as already announced by Alain Brobecker in a recent 
posting:


> And Bernd also promises a D23/13!!!


Bernd Schwarzkopf has improved again his own length
record for unique retractions in a Type D problem.

In fact, in his 23 pieces position, the last 14
single moves are uniquely determined:

Bernd Schwarzkopf

7B/1p1p2p1/6p1/8/5P2/3PPrP1/P1Prqppb/K1kBBB1b

11+12=23  Last 14 single moves, Duplex.

If White starts retracting, the last 15 single moves
are determined:

-1.h7-h8=B Bg1-h2 -2.h6-h7 Bh2-g1 -3.h5-h6 Bg1-h2 
-4.h4-h5 Bh2-g1 -5.h3-h4 Bg1-h2 -6.h2-h3 h3xNg2 
-7.Nh4-g2 Bg2-h1 -8. Nf5-h4 

If Black starts retracting, the last 14 single moves
are determined:

-1. .. Bg1-h2 -2.h7-h8=B Bh2-g1 -3.h6-h7 Bg1-h2 
-4.h5-h6 Bh2-g1 -5.h4-h5 Bg1-h2 -6.h2-h4 h3xNg2 
-7.Nh4-g2 Bg2-h1 -8.Nf5-h4 


But that's still not the absolute length record for 
a Type D problem.
Bernd was able to produce a position in which the
last 15 single moves are uniquely determined:


Bernd Schwarzkopf

7B/1p1p1pp1/8/8/4PP2/1PPPkrP1/bPKNrppb/NQn1qb2

12+14  Last 15 single moves, Duplex.

If White starts retracting, the last 16 single moves
are determined:

-1.h7-h8=B Bg1-h2 -2.h6-h7 Bh2-g1 -3.h5-h6 Bg1-h2 
-4.h4-h5 Bh2-g1 -5.h3-h4 Bg1-h2 -6.h2-h3 h3xBg2 
-7.Bh1-g2 h4-h3 -8.Bg2-h1 h5-h4 

If Black starts retracting, the last 15 single moves
are determined:

-1. .. Bg1-h2 -2.h7-h8=B Bh2-g1 -3.h6-h7 Bg1-h2 
-4.h5-h6 Bh2-g1 -5.h4-h5 Bg1-h2 -6.h2-h4 h3xBg2 
-7.Bh1-g2 h4-h3 -8.Bg2-h1 h5-h4



Regards,

  mario