No.986 
Geoff Foster (Australia)

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Original Problems, Julia’s Fairies – 2016 (I): January – June

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


No.986 by Geoff Foster – Mates by a single neutral piece. The problem is inspired by No.985. (JV)


Definitions:

KoBul Kings: When a piece (not a pawn) of his own side is captured, a King transforms into a Royal piece of the same type as the captured one. When the King is in the form of any Royal piece and there is a capture of one of the pawns of his own side, he becomes a normal King again. Captures are illegal if they result in self-check by the transformed King.

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


No.986 Geoff Foster
Australia

original – 04.01.2016

Solutions: (click to show/hide)

neutral Ke3 Pa2e7

h#2.5          b) nPa2→c2       (0+0+3)
Phantom Chess
KoBul Kings


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Diyan Kostadinov
Diyan Kostadinov
January 4, 2016 10:24

Nice AUW, very clear problem – bravo, Geoff!

Diyan Kostadinov
Diyan Kostadinov
January 4, 2016 10:40

Actually the last moves in both solutions should be 3…nKxe2(e2=rB) and 3…nKxc1(c1=rS) (instead of 3…nrBxe2 and nrSxc1), because the neutral King is still on its “King” phase before the capture.

seetharaman
seetharaman
January 4, 2016 11:27

hm…. so in Phantom chess, royal pieces have no Phantom power?

Joost
Joost
January 4, 2016 15:40
Reply to  seetharaman

See definition: Any unit except a king may move either normally (from its current square) or as though from its Circe rebirth square.

A royal piece is ‘a king’.

seetharaman
seetharaman
January 4, 2016 16:39
Reply to  Joost

Thanks Joost. Next question:

Where will a royal knight reappear on being captured in ‘rex-inclusive circe’?

seetharaman
seetharaman
January 4, 2016 11:52

The neutral king is confusing.

In the following setting can someone tell me why 1.a8B is not mate but Popeye gives 1.Qh2#

nKh1, nPa7, WQg3. WBb8.

Joost
Joost
January 4, 2016 12:43
Reply to  seetharaman

a8=nB is selfcheck.

seetharaman
seetharaman
January 4, 2016 13:17
Reply to  Joost

so.. why .1.Qh2 is not selfcheck in that scheme?
On that logic why the mating moves in 986 are not selfcheck?

Georgy Evseev
Georgy Evseev
January 4, 2016 13:22
Reply to  seetharaman

> why .1.Qh2 is not selfcheck in that scheme?

White queen cannot check white king

> On that logic why the mating moves in 986 are not selfcheck?

Because “phantom check” squares are different for white and black.

Georgy Evseev
Georgy Evseev
January 4, 2016 14:17
Reply to  Georgy Evseev

Example (phantom chess):

White want to play npb7-b8=nB

if neutral king on a3 – illegal selfcheck;
king on g3 – illegal selfcheck;
king on e3 – legal check to black;

seetharaman
seetharaman
January 4, 2016 15:18
Reply to  Georgy Evseev

Because “phantom check” squares are different for white and black. >>>>>>
Thanks. I missed that point !

Nikola Predrag
Nikola Predrag
January 4, 2016 17:23

Diyan, you should define the nature of the NEUTRAL Kobul King.
When White makes a capture, only BLACK Kobul King transforms.

So a neutral Kobul King might be compound e.g. as
neutral “wK+bB”.

By its nature, a neutral piece is affected differently when White or Black captures it – it has two different rebirth squares.
And some conditions, like BackToBack, make a different effect on the white/black component of a neutral piece.

And Kobul King should be affected only when the opponent makes a capture, unless the inventor has explicitly defined otherwise.

It would be probably interesting to have 2 types of neutral Kobul Kings.

Diyan Kostadinov
Diyan Kostadinov
January 4, 2016 21:56

Nikola, let we do not make things more complicated than they are. Everything with neutral King being under the KoBul Kings condition is simple – the neutral King is combine white and black so it changes on all piece captures (white/black/neutral) and take the nature of the captured piece. Of course it take back on its King’s phase when a pawn being captured.

The specific colour differences with the neutral King can be seen for example with a combination with Anti-Circe type conditions in case of captures by the neutral King (neutral Royal Piece). In this case after the transformation the Royal Piece reborn on game array square according that which side did moved – i.e. if the neutral King from a1 capture black Bishop on a2 moved by white side it transform to neutral Royal Bishop and reborn on c8: 1.nKxa2=nrB(nrBc8)

It is very IMPORTANT that in all captures the King (white, black or neutral) transforms ONLY its nature and NOT its color!

Juraj Lörinc
January 4, 2016 23:17

Having neutral hybrid on the board, as Nikola suggests, would be confusing. I think the way neutral king is used in the present problem, is simpler and offers better possibilities for understandable problems.

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