Julia's Fairies

No.773,774 (GF)

No.773, 774 
Geoff Foster


Original Problems, Julia’s Fairies – 2015 (I): January – June

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No.773, 774 by Geoff Foster – Each problem has a twin in which a black King is replaced by a neutral one! (JV)


Phantom Chess: Any unit except a king may move either normally (from its current square) or as though from its Circe rebirth square if the latter is vacant.

Circe: Captured units (not Ks) reappear on their game-array squares, of the same colour in the case of pieces, on the file of capture in the case of pawns, and on the promotion square of the file of capture in the case of fairy pieces. If the rebirth square is occupied the capture is normal.

No.773 Geoff Foster

original – 10.04.2015

Solutions: (click to show/hide)

Black Kg3 Neutral Pg7 Pa2

h#2                b) nKg3         (0+1+2)
Phantom Chess

No.774 Geoff Foster

original – 10.04.2015

Solutions: (click to show/hide)

Black Kh7 Neutral Pd2 Pg2

h#3                b) nKh7         (0+1+2)
Phantom Chess

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April 11, 2015 15:51

In 774, how is it a check in 2.d1=nS+ and a mate in 3…nSd1-a3#?

Nikola Predrag
Nikola Predrag
April 11, 2015 17:30

In Phantom chess, a Piece can make a standard move from the square it occupies, but also any move which it would be able to make from its rebirth square (if that square is empty).

So, both White and Black can move the neutral S from d1 to b2,c3,e3,f2. But White can also move nSd1 (as though from b1) to a3,c3,d2 and Black can move it (as though from g8) to e7,f6,h6.

That is why d2-d1=nS+ is a legal black move, only white is checked.
In the end, after 3…nSd1-a3#, d1 is empty and if White was on the move, he would be able to move nQ (as though from d1) to h5, so Black is checked.
The move 3…nSd1-a3 is not a selfcheck because Black can move nQ as though from d8 (and not d1).

nS is superfluous in the mate, but White can’t move it randomly in the mating move.
Black must not be allowed to parry the check by moving nS back to d1 or to interfere on the line d1-h5.

Kjell Widlert
Kjell Widlert
April 11, 2015 22:31

In both problems, the a) solution will not work with a neutral K because of selfcheck – quite obvious, isn’t it?
To mate a nK with a neutral, you need a neutral that moves differently for White and Black (so only White can capture the nK with it). With “orthodox” neutrals, the only possibility is mate with a nP. But in Phantom Chess, all neutrals move partly differently for White and Black!

Kjell Widlert
Kjell Widlert
April 11, 2015 22:36

I like the subtle twinning device! It is somewhat paradoxical that different solution work with a black and a neutral K.
I also like the way the king’s field is guarded in part b) of 773: together with its own phantom, the nQ guards all eight flights of the nK!

In a h=, one could imagine a neutral triplet with the K being a) white, b) black, c) neutral. I don’t think such a problem exists – yet.

April 12, 2015 08:36

Thank you, Nikola for patiently explaining to me!
In 774, 2.d2-d1=nS+ is fine but 3…nSd1-a3# is too clever indeed.

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