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)
Definitions:
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.
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No.753 Julia Vysotska
Latvia
original – 22.03.2015
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Solutions: (click to show/hide)
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White Kg8 Pe4
Black Kc4 Bb3 Sa6 Pb5 Pf4 Pc3
Neutral Bg5 Sg4 Ph5
h#2 2 solutions (2+6+3)
Back-To-Back
Take & Make
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1.b5-b4 nBg5-h3 {(1...nPh6?)} 2.nPh5*g4-f2 nBh3-f1 # {
(C+ by Popeye 4.69 and WinChloe 3.31)}
1.Sa6-b4 h5-h6 {(1...nBh3?)} 2.nPh6*g5-e6 nSg4-e5 # {
(capture of a piece in BTB pair on the 2nd move works differently
in Popeye 4.69, C+ by WinChloe only!)}
Thematic complex:
Neutral pieces in a Back-To-Back+Take&Make play. Destruction of the initial BTB mechanism (nSg4/nBg5) and creation of two new BTB mechanisms - nBf1/nPf2 (I) and nSe5/nPe6 (II) with an active use of the nP and T&M. BTB-specific pin of the mating neutral piece. Special form of Zilahi with a change of function of nS/nB. Black Self-blocks on b4, combined with Anti-dual. Model mates. Meredith.
Detailed explanation to some BTB & T&M moves:
- Different usage of BTB and T&M during the play:
- in the first solution BTB and T&M are used in two different moves:
1...nBg5-h3 moves as white using the role of nSg4 by BTB;
2.nPh5*g4-f2 - T&M capture by nP
- in the second solution BTB and T&M are used in the one move:
2.nPh6*g5-e6 - T&M capture of the piece in BTB pair, so the captured piece has a role of nSg4 by BTB and it is used by the nP to move to e6. (this type of capture works in WinChloe only!)
- A specific BTB pin of the neutral mating piece, identical in the both solutions (shown for the first time):
- in the first solution after 2...nBh3-f1 # - a mate is given by nBf1; nBf1 can't escape as being black it has a role of nPf2; nPf2 being white guards flights c5 & d4 taking role of nBf1;
- in the second solution after 2...nSg4-e5 # - a mate is given by nSe5; nSe5 can't escape as being black it has a role of nPe6; nPe6 being white guards flights c5 & d4 taking role of nSe5.
(Author)
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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.
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.
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.
Yes, Nikola, for the neutral piece in a pawn’s role it is block by the edge of the board or by the wPe4. But I was thinking about the giving pawn’s role to the neutral piece to be able to block it. Maybe it would be better to call it as a mechanism holding a neutral piece, changing it’s role so it can be blocked/stopped.
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).
There is a difference between BTB and FTF neutral pair as an exchange of role either happens or not depending on the piece used on the white or black move.
Let’s take my pair nBg5/nSg4 as an example:
1) In case of BTB the exchange of role happens if the white piece is on the top. So, on the white move the top piece, nBg5, would move as Knight, but on the black move it would not change a role, but would move as Bishop. The same, on the white move the bottom piece nSg4 would keep Knight’s role, but on the black move it would change a role to Bishop’s.
2) In case of FTF the exchange of role happens if the black piece is on the top. So, on the black move the top piece, nBg5, would move as Knight, but on the white move it would not change a role, but would move as Bishop. The same, on the black move the bottom piece nSg4 would keep Knight’s role, but on the white move it would change a role to Bishop’s.
The idea is the same, but change of roles happens oppositely.
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.
Thank you, Mike! I also appreciate your and Juraj’s (March 22, 2015 at 23:39) comments supporting/accepting such interpretation of neutral BTB pair and mating finals in my problem. I also needed some time to convince myself that such interpretation might be acceptable, and I’m still thinking about all possible pro and contra arguments. So, I’m very interested in different views! In a case if the interpretation can be generally accepted, I’d try some more ideas for composing.. 🙂
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.
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.
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!
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#
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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#
Thank you, Nikola! To my opinion, your problems shown in the comment are worth to publish. Would you like me to do so? Problems shown in comments only won’t participate in the informal tournament…
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.