Original Problems, Julia’s Fairies – 2014 (II): May – August
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No.547 by Rainer Kuhn – A very specific twin of this problem shows the different implementation of combination Mirror-Circe + Take&Make in two solving programs – Popeye and WinChloe! Author mentions also that “the idea was reinforced by the comment from Georgy Evseev to No. 529.” (JV)
Take & Make: Having captured, a unit must immediately, as part of its move, play a non-capturing move in imitation of the captured unit from the capture-square. If no such move is available, the capture is illegal. Promotion by capture occurs only when a pawn arrives on the promotion rank as the result of a take&make move. Checks are as in normal chess: after the notional capture of the checked K, the checking unit does not move away from the King’s square.
Mirror Circe: Like Circé, but the rebirth square of a piece is the square occupied at the beginning of an orthodox game by a piece of the same kind and of the other side. Related to the square they occupied before the rebirth:
- Rooks, Bishops and Knights are reborn on the square of the same color.
- Pawns (including fairy Pawns) are reborn on the same file.
- Other fairy pieces are reborn on the same file and on the promotion rank of the other side.
No.547 Rainer Kuhn
original – 21.05.2014
Take & Make
a) priority to Mirror-Circe
b) priority to Take&Make
Solutions: (click to show/hide)
a) 1.- Bf3! 2.a1=B B×g4(Bd7;Bf1) 3.Be5 K×f1(Ka6) 4.Bb8 Bc6#
b) 1.- Bh1xe4-e3[+bPe2]! 2.f4xe3-a7[+wBf8] Ke1xf2-f4[+sRa1] 3.Ra1-f1 + Kf4xg4-c8
(a) C+ WinChloe 3.25 ; b) C+ by Popeye 4.65)
As the problem No. 529 was published with JF I only had a little anticipation that there exists a clash between the fairy condition Take&Make and Mirror-Circe (or any other form of Circe). The definition gap occurs if a capture (Take-Move) happens on a rebirth square of the captured piece. It’s not clear what will come first: The possible Mirror-Circe rebirth and then the Make-Move or execute completely Take&Make and then the possible Mirror-Circe rebirth. In dependence on this a solution can be prevented or enabled. The solving program WinChloe uses the first definition and Popeye the second. So the idea for this problem was born to show both possibilities in one position. As well the idea was reinforced by the comment from Georgy Evseev to No. 529. (Author)
The author correctly states that it all depends on the prioritization of fairy conditions. So why doesn’t the twinning point out exactly that difference? It might sound funny and add a cryptic touch to refer to computer programs instead, but this approach a) fosters obscurity and b) will not stand the time … whereas this nice echo mate will surely be remembered as an excellent pioneer illustration of the prioritization twin, even if it wasn’t the first one, see e.g. the Special Prizes of the 4th Bulgarian Wine Tourney by Caillaud and Argirakopoulos.
After Manfred’s comment author asked me to change the names of twins:
a): from “C+ by WinChloe” to “priority to Mirror-Circe”
b): from “C+ by Popeye” to “priority to Take&Make”
I’d like to mention again, that WinChloe always gives priority to Circe, while Popeye gives priority to Take&Make.