Julia's Fairies

No.621 (SL)

Sébastien Luce 


Original Problems, Julia’s Fairies – 2014 (III): September – December

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Please send your original fairy problems to: julia@juliasfairies.com

No.621 by Sébastien Luce – A problem inspired by No.620 – Just one royal piece on the board and serial mate in two phases! (JV)


Sentinels Pion neutre: When a piece (Pawn excluded) leaves a square outside the first and last rows, a white piece leaves a wP, a black piece leaves a bP and a neutral piece leaves a nP unless 8 Pawns of that color are already on the board.

Einstein chess: All units (Ks excluded) change their type when they move, according to a precise pattern. For non-capture moves: Q>R, R>B, B>S, S>P, P remains P. For capture-moves: R>Q, B>R, S>B, P>S, Qremains Q.

Royal piece: Piece that executes a function of the King on the board.

No.621 Sébastien Luce

original – 12.10.2014
Dedicated to Peter Harris!

Solutions: (click to show/hide)

neutral royal ra7

ser-#9       b) nrRa7→d7    (0+0+1n)
Sentinels Pion Neutre
Royal piece Ra7

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Peter Harris
Peter Harris
October 13, 2014 10:25

Good Sebastien and thank you for the Dedication.
I would mention that my 620 is not to do with an ever-changing Royal piece – it is much simpler. Einstein introduces something additional which ruins the simplicity for which I was seeking.
As an aside: I would say 620 can be solved whereas yours cannot be – that is if there is a distinction between a human SOLVING a problem and a computer FINDING solutions!
I am these days trying to make problems for solving.

Peter Harris
Peter Harris
October 13, 2014 12:23

Sebastien, you may like to see these three.

brBd7 h#2 sent pionad (b) B > Ro [0+1]
wrRd4 brRe5 h#3 (a) sent (b) sent pionad [1+1]
nrPe2 nPc2 sent pionn (a) h#3 (b) ser-h##5 [0+0+2]

As you see they are short and with sentinelles only.

Kjell Widlert
Kjell Widlert
October 13, 2014 15:40

The twinning seems to be missing from the stipulation – presumably b) nRa7>d7 ?

S. K. Balasubramanian
S. K. Balasubramanian
October 13, 2014 17:29


The definition of Einstein Chess (though known) is missing.
Further, it looks that there are cooks:

(a) 1.nrRa4=nrB (+nPa7) 2.nrBb5=nrS (+nPa4) 3.nrSxa7=nrB (+nPb5) 4.nrBc5=nrS (+nPa7) 5.nrSxa4=nrB (nPc5) 6.nrBxb5=nrR (+nPa4) 7.nrRb7=nrB (+nPb5) 8.nPb6 9.nBa8=nrS (+nPb7) #

(b) 1.nrRd4=nrB (+nPd7) 2.nrBc5=nrS (+nPd4) 3.nrSxd7=nrB (+nPc5) 4.nrBb5=nrS (+nPd7) 5.nrSxd4=nrB (nPb5) 6.nrBxc5=nrR (+nPd4) 7.nrRc7=nrB (+nPc5) 8.nPc6 9.nBb8=nrS (+nPc7) #

October 13, 2014 19:18
Reply to  Julia

It remains to know why “Bala’s solutions” are unsound. It seems the move 2.nrBb5=nrS(+nPa4) is illegal. Indeed the possibility a4xrSb5 implies in some sense that black is then under check, which is illegal in a direct series problem (before the terminal mating move).

S. K. Balasubramanian
S. K. Balasubramanian
October 13, 2014 19:58

Julia says that the computer does not show any cook. These cooks I found by manual solving. I strongly feel that the two cooks which I have mentioned are there. Might be the Popeye has some bugs in solving this fairy condition. Can anybody tell where I am wrong?

October 13, 2014 20:27

My above explanation doesn’t convince you? At least this is the same way Popeye is thinking: with a neutral royal Bishop a4 as only piece on the board, and same conditions as in Sébastien’s problem, legal moves are:

1.nrBa4-d1=S[+nPa4] !
1.nrBa4-c2=S[+nPa4] !
1.nrBa4-e8=S[+nPa4] !
1.nrBa4-d7=S[+nPa4] !
1.nrBa4-c6=S[+nPa4] !
1.nrBa4-b5=S[+nPa4] + !

In your “solution” a) you are using the above last possibility at move 2. This is illegal in a series problem as it is a checking move (as denoted by the program).

Kjell Widlert
Kjell Widlert
October 13, 2014 21:04
Reply to  dupont

The explanation convinces me, at least. In a normal series problem (not parry series) it is illegal to check Before the last move, as the side being checked must be given a chance to escape check.

Peter Harris
Peter Harris
October 13, 2014 22:50

Dear SKB,

I am smiling to myself when I read your earnest comments!

With Sentinelles [or Sentinelles PionNeutre] a Neutral Royal piece moving to either of the adjacent diagonal forward* squares checks Black. One is not allowed to check Black midway through a Ser- # [and blithely carry on!]

It is as simple as that.

[Therefore both of your second moves are not allowed].

* Moving backwards would be an illegal self-check.

S. K. Balasubramanian
S. K. Balasubramanian
October 14, 2014 03:28

Thanks to all, Yes I realize now that the second moves in both my solutions are illegal. It didn’t strike me that those moves are checking moves (to bK). Sorry again Sabastein. It is my mistake and I sincerely apologise.

S. K. Balasubramanian
S. K. Balasubramanian
October 14, 2014 04:47

Dear Dupont,

Your reply on Oct 13, 2014 at 19:18 did not appear in my computer before I posted my query subsequently. I posted my query yesterday at 19:58 . So, sorry that I couldn’t see your first explanation.


Sebastien Luce
Sebastien Luce
October 14, 2014 16:06

What a discussion for only one piece !!
and no problem M.Balasubramanian. It shows that like in your n°617 in Back to Back + Madrasi, very often when you mix two (or more) fairy conditions, the effects become very “strange”… but also very interesting to study !
– SL

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