[Retros] Attached article [Soltis on proof games]

[Mario Richter]

Thanks, Steve!

NDE> ... at the beginning the -b7 solution is twice as long as necessary...

And at the end, in the shortest double-maximummer mating game,
the mate can also be given on c7 ...
1.Ng1-h3 Nb8-c6 2.Nh3-g5 Ng8-h6 3.Ng5-e6 Nh6-f5 4.Ne6xd8 Nf5-h4 
5.Nd8-e6 Nc6-d8 6.Ne6xc7#


Another imitation game, in which only bishops and pawns move:
1.b2-b3 b7-b6 2.Bc1-a3 Bc8-a6 3.e2-e3 e7-e6 4.Bf1-d3 Bf8-d6 
5.Bd3xh7 Bd6xh2 6.f2-f3 f7-f6 7.Bh7-g6#
(If promotions are allowed, then there exists games, in which
White mates by e.g. 6.c7xd8=Q#)

The 15 progressively longer moves problem seems indeed to have
a unique solution.

Best,
  mario