Julia's Fairies

No.753 (JV)

Julia Vysotska


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

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No.753 by Julia Vysotska –  Back-To-Back specific pin of the mating neutral piece! Hopefully, shown for the first time. 🙂 

I should admit, that the solutions might look weird here and the interpretation of neutrals’ behavior with Back-To-Back can be a topic of some discussions. Myself, I find such interpretation reasonable. (JV)


Back-To-Back: When pieces of opposite colors stand back-to-back with each other on the same file (white piece is on the top of black!), they exchange their roles. A pawn on the first rank cannot move. Any piece can make an en passant capture when it has got a role of Pawn by Back-To-Back.

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.

No.753 Julia Vysotska

original – 22.03.2015

Solutions: (click to show/hide)

White Kg8 Pe4 Black Kc4 Bb3 Sa6 Pb5 Pf4 Pc3 Neutral Bg5 Sg4 Ph5

h#2              2 solutions       (2+6+3)
Take & Make

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March 22, 2015 21:07

Applying BTB to neutral pieces is controversial. In the mating position one can argue that the pawn and the mating piece are both white, hence the pawn does not guard any square. If they are both white, then there is no pin and the mating piece can be moved away.

Juraj Lörinc
Juraj Lörinc
March 22, 2015 23:39
Reply to  seetharaman

But this way of thinking about neutral pieces is not correct. Neutral pieces are not alternatively black and white. They are neutral, full stop. Their basic properties by definition are: they can be moved by both sides, they check both sides, they can be captured by both sides.
As a consequence, in the mating position of the first solution, nBf1 does not change its movement for White, as there is no black piece (or neutral piece that could be moved by Black too) on imaginary square f0. nPf2 changes its movement for White because of nBf1. Then the rest is analogous.
I agree with Julias (and WinChloe’s) interpretation of capture of nBg5 in the second solution. Bg5 is captured by Black, therefore its movement for White counts for Make part of T&M move.

Nikola Predrag
Nikola Predrag
March 22, 2015 22:41

There is no pin. nSe5 is BLOCKED by wPe4 and nBf1 by the edge of the board.
In the final positions, Black would be able to move the checking neutral piece as a bP, if there was a legal Pawn-move.

March 23, 2015 01:26

After 1.b4, WinChloe considers that legal moves from nSg4 are still Knight moves, so there is no more “exchange” of roles between the actors of a neutral BTB pair (the nBg4 is also moving as a Knight, as in the solution). Why and isn’t it a difficulty regarding the philosophy of the concept?

More generally, which are the rules governing a neutral BTB pair? Are they the same than for a FTF pair? (to my mind it should be as I see no difference between being back to back and face to face for neutral units).

Mike Neumeier
Mike Neumeier
March 23, 2015 05:50

Nice problem, Julia. A good thematic pair. I do see how both mates can be controversial, but I agree both mate firing neutrals played by White are stuck when Black tries to attempt escape. Black is not able to move these away, and the firing power by White must remain thereby. In each case, the firing unit is the “under” (Black) piece in BTB (where only “X over Black” can apply), and in each of your mates you arranged for giving the firing unit (now Black’s) movement powers (Pawn in both cases) that he cannot use to make an escaping move. Well done.

Kjell Widlert
Kjell Widlert
March 23, 2015 19:05
Reply to  Julia

Sorry, I can’t give you a different view – for I happen to agree! This interpretation of neutral BTB pairs (or neutral FTF pairs) is really the most logical one:

In BTB, when White moves the upper piece of a neutral pair, he is treating it as white – and it gets its power of movement from the black part of the lower piece. When Black moves the same upper piece of a neutral pair, he is treating it as black, so there is no BTB situation, so the piece has its normal power of movement.

And the other way round for the lower piece of the pair. And everything the other way around again for FTF!

This is the same way of thinking as for Madrasi with one or two neutrals (I hope I’m right), and also the same way of thinking as for Annan Chess with neutrals. (Annan Chess is much like FTF and BTB, but concerns pieces of the same colour, and only the upper piece – from the point of view of the side that is moving it – changes its power of movement.) See for example the announcement of the Arnold Beine JT on the website of Die Schwalbe.

Georgy Evseev
Georgy Evseev
March 23, 2015 11:30

It is interesting definition, when “white” part of a neutral piece does not prevent black from moving this piece itself, but at the same time strictly affects the movement of another piece due to BTB effect.

(I would say that the side to move should have right to choose if BTB effect applied or not. Also 2.hxg5-e6 in second solution looks suspicious for me.)

At the same time I am not against something like fairy condition “strict neutrals”, which postulates that if any bicolor effect is applicable to neutral pieces, it should be applied forcefully. For example, historically (after an article by Petko Petkov) such “strict neutrals” condition is applied to Madrasi with neutral pieces.

Kjell Widlert
Kjell Widlert
March 23, 2015 19:39
Reply to  Georgy Evseev

2.hxg5-e6 may look suspicious, but I think it is correct.

We discussed recently in Connection with another problem how T&M + BTB (without neutrals) should work when one of a BTB pair is captured. Everyone (?) agreed that when Black captures the upper piece of the pair, the “make” part of the move should be according to the present power of movement of that piece, i.e. the movement of the lower piece of the BTB pair, rather than the normal movement of the captured piece.

With neutrals, we can reason the same way. Black captures the nBg5, so he is treating it as white; and for White, the captured piece currently has the power of a S (from nSg4). So the “make” part should be a S move, such as g5-e6!

Nikola Predrag
Nikola Predrag
March 24, 2015 02:03

Julia, your idea is nice and clearly realized.
A mating neutral piece is incarcerated due to BTB effect. Perhaps the “BTB incarceration” would be more proper.

Pin is about the “illegal selfcheck”.
Here are two original examples, one with reciprocal thematic functions and one with echo mates:

White Pf3 Kb2; Black Qa6 Pf4 Kd3; Neutral Be6 Sg6
h#2.5; 2 solutions; Condition BackToBack
1…Kc1 2.nSe7 nSc5+ 3.Qc4 nBxc4#
1…nBf5 2.Qa5 Kb3 3.Qd2 nSxf4#
White Kd1; Black Re5 Pg5 Kg4; Neutral Bb5 Sc4
h#; 2 solutions; Condition BackToBack
1…nSb6 2.nBd6 nSd5 3.nSe6 Ke2 4.Kf4 nBxe5#
1…nBc6 2.Re4 nSe5 3.Kf3 Ke1 4.g4 nBxe4#

Nikola Predrag
Nikola Predrag
March 24, 2015 19:06

Each one of the two examples has one very poor solution, where only White moves the Neutrals and everything is merely about reaching the final thematic mates.
I hate such a dull extension of the play. One might say that the pieces are “perfectly” positioned initially, enabling 2 phases without twinning.
But from the aspect of the thematic content, they are actually badly positioned.

I (or anyone else) should try to improve it, at least by enriching the play of Neutrals.
Of course, the diagrams could be added to my comment, for easier readers’ perception.

There’s another possibility but I’m afraid that nobody would support it.
I would personally publish such stuff as the “original examples”.
A true problem requires an economical realization of some thematic idea.
A prevalently non-thematic play might suffice as a tool for an example of some thematic feature.

Would love your thoughts, please comment.x