Fairy chess composition
 No.1293 Hubert Gockel (Germany) Original Fairy problems JF-10/2017-3/2018: October’2017 – March’2018

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 No.1293 Hubert Gockel Germany original – 30.03.2018 Solution: (click to show/hide) white Qa3 Ba8 Re5f8 Sg6 Bg3 Kg8 Pb6c7f5 black Kd6 Sb5c4 Qc2 Pc5d7e6 #2                                           (10+7) AMU 1.R:e6#?? / Q:c5#?? / c8=S#?? These thematic mates are illegal because each mating piece is observed twice. In each of three defences Black withdraws two observations of two pieces in cyclic fashion so that two mates mates should be possible at the same time. But thanks to cyclic dual avoidance only one is. (Author) 1.Sg6-e7 ! threat: 2.Se7-c8 # 1...Sc4*b6 2.Re5*e6 # {A (2.Q:c5+? B Q:c5!)} 1...Sb5-a7 2.Qa3*c5 # {B (2.c8=S+? C S:c8!)} 1...Kd6*e7 2.c7-c8=S # {C (2.R:e6+? C d:e6!) (C+ by Popeye 4.79)}

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Juraj Lörinc
March 30, 2018 19:51

Instructive example of cyclic dual avoidance and a new proof of AMU condition usability for various effects.

Geoff Foster
May 14, 2018 01:04

An interesting problem with a good flight-giving key. The dual avoidance uses 3 different mechanisms: opening of black line, guard of mating square, and move of King so that white move is not a double-check.

Geoff Foster
May 14, 2018 01:08

However it is a pity that after 1…Kxe7, 2.Qxc5 would not be mate anyway.

seetharaman
May 14, 2018 19:55

Can d7 be shifted to f7?

Geoff Foster
May 15, 2018 13:38

: I don’t understand what you mean about shifting d7 to f7. The bPd7 is necessary in order to block the square d7.

seetharaman
May 17, 2018 23:04