[Retros] Christmas Contest 2002 of "Stuttgarter Zeitung"

[Jens Guballa]

Here is the result of the Christmas Contest 2002 of "Stuttgarter
Zeitung" by Harald Keilhack:

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115 participants sent their solutions, whereby the following prices
were drawn by lot (among 101 correct solutions):

1st price (micro stereo system): P. Schmitz
2nd price (espresso machine)   : R. Thomaier
3rd price (cordless telephone) : M. Richter

Here are the solutions:

A: Guenther Weeth, Stuttgarter Zeitung 2002
Almost all participants found the correct solution: White retracts 
f5:g6 e.p. and mates with Bg7#.

B: Guenther Weeth, Stuttgarter Zeitung 2002
Back: d7:Be8=N Forward: d7:Bc8=N#. Nice exchanges of the pieces Bc8
and Ne8. 

46 participants tried to solve the "expert" competition (problems C-E),
only four of them succeeded without faults: Jens Guballa, Henrik Juel,
Kurt Lorenz and Bernd-Martin Schuh.

Solutions with minor faults were sent by M. Bauer, Gabriele Bauers, D.
Fauth, N. Geissler, R. Kraetschmer, T. Lutzius, E. Mozer, M. Richter,
and B. Schwarzkopf, they all will receive also a book price.

Problem E caused the biggest despiration, but 18 participants could
solve it. The pitfalls of C (16 correct solutions) and D (7 correct
solutions) were even more "selective".

C: Werner Keym, Stuttgarter Zeitung 2002
a) There are five solutions: 
   - Back: a7-a8=B# Forward: a7-a8=Q# (last black move: g2-g1=B or
                                       h2/f2:g1=B)
   - Back: b7:Ba8=B# Forward: b7:Ba8=Q#
   - Back: b7:Qa8=B# Forward: b7:Qa8=Q#
   - Back: b7:Ra8=B# Forward: b7:Ra8=Q#
   - Back: b7:Na8=B# Forward: b7:Na8=Q#
b) Only 3 solutions:
   - Back: g7:Qh8=B# Forward: g7:Qh8=Q#   
   - Back: g7:Rh8=B# Forward: g7:Rh8=Q#   
   - Back: g7:Nh8=B# Forward: g7:Nh8=Q#   
   The retraction of g7:Bh8=B# and h7-h8=B# fails, because there is
   no last black move.
c) Only one solution:
   Back: e5:d6e.p# Forward: B:d5# (last black move was d7-d5, last white
   move was e4-e5+)
   The retraction of c5:d6e.p#  fails, because the check of the Bh1
   is illegal. 
d) No solution.

D: Guenther Weeth
Is everything correct? No, there are two solutions:
a) Back b5-b4, Bc6:Ra8 Forward: c5:b6e.p.#
   There must be a rook on a8; if the square a8 would be left free, then
   the last move could have been (after retraction of Bc6-a8): Rb7:Na7+,
   Ka8:Ra7. Placing another black piece on a8 is also not possible,
   because that piece could have made the last move.
b) Back Kb7-a8, a7-a8=B+ Forward: a7:Nb8=Q#.

The "hidden" rook on a8 caused more particapants to fail than the 2nd
solution. The 2nd solution was intended by Weeth, otherwise he would
have placed a white pawn on a6.

E: Josef Haas, Schach 1973
With black to move the position is legal, as shown in the following
example:
1.d3 b6 2.h3 Bb7 3.a4 Be4 4.dxe4 Na6 5.Qd6 cxd6 6.b4 Rc8 7.c4 Rc5 8.Ra3
Rg5 9.Nc3 Qa8 10.Nf3 Qd5 11.c5 Qf5 12.c6 h5 13.c7 Rg6 14.exf5 Rh7
15.fxg6 Nb8 16.gxh7 g6 17.Ne5 Bh6 18.Nd5 Kf8 19.c8=Q+ Kg7 20.Qc4 Bf4
21.Nc7 Bh2 22.Qf4 Bg1 23.Rh2 dxe5 24.Rg3 exf4 25.Kd2 fxg3 26.Ke3 Kf6
27.Kf3 gxh2 28.Bh6 Kf5 29.Bf8 Nf6 30.Ne8 Kg5 31.Ng7 Kh6 32.Kg3 Ne4+
33.Kh4 Ng3 34.a5 Nh1 35.g3 Na6 36.Bg2 Nc7 37.Bf3 Ne8 38.Be4 Nc7 39.Bc2
b5 40.Ba4 bxa4 41.b5 Ne8 42.b6 Nc7 43.b7 Ne6 44.Ne8+ Ng7 45.Nd6 a6
46.Nb5 axb5 47.a6 b4 48.a7 g5#
Other last moves than a6-a7 will lead to a retro stalemate or to a
lockout of important pieces. 

Some solver proposed another solution (with white or black to move),
but they retracted only to an illegal position.

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Best regards,
Jens