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MatPlus.Net Forum General Extreeeeme Knight Wheel
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(1) Posted by Hauke Reddmann [Saturday, May 13, 2017 19:36]

Extreeeeme Knight Wheel

Does anyone know a problem with eight knights (black or white)
standing on the fields of a knight wheel? (I only checked the
#2 collection, but to no avail. I could probably compose
such a problem myself within ten minutes, just for teh lulz...)

The less fairy, the more an impressed Hauke :-)
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(2) Posted by Geoff Foster [Sunday, May 14, 2017 03:34]

Hans Gruber & Rudolf Queck, Problemkiste 1987
(= 8+5 )
h#4 4.1

1.S3d4 Sbd2#
1.Sfe3 Sfg3#
1.Sde5 Sdc5#
1.S5f4 Shf6#

Nikita Plaxin (dedicated to L.Loshinsky)
Caissas Schlossbewohner I 1983
(= 1+13 )
Last Move?

(The bQ on g8 and white piece on a8 had protected the wK from check from a black R or S playing to a white square).

Frantisek Sabol, Commended, feenschach 2001
(= 7+15 )
#2 Mars Circe

1.Re1! (>2.Bxb2#)
1...Sf5xh6 2.Sf5
1...Sf7xh6 2.Sf7
1...Se4xh6 2.Se4
1...Se8xh6 2.Se8
1...Sc4xh6 2.Sc4
1...Sc8xh6 2.Sc8
1...Sb5xh6 2.Sb5
1...Sb7xh6 2.Sb7
1...Rh3+ 2.Sxh3
1...Rf3+ 2.Sxf3
1...Ree2+ 2.Sxe2
1...Bxh6 2.axb3

In Mars Circe, pieces can only capture by returning to their game array square and capturing from there. So here the Kings do not check each other because they can only capture from e1/e8. The threat 1.Re1 vacates c1, threatening 2.Bxb2 (capturing from c1). This is mate because the bKa3/bBa1/bSc4 can only make capturing moves from e8/f8/g8 respectively. Any of the 8 bSs on white squares can capture the wBh6 (from g8), but each such capture vacates a square for the wSd6, which by moving to a white square gives mate (from b1). The bRe3 can defend by moving to a white square, because it then checks the wK (from a8). However this allows the wSd6 to make a capturing move on h3/f3/e2 (from g1), which by moving to a white square gives mate (from b1). The defence 1.Bxh6 (from f8) allows the battery mate 2.axb3 (mate by wRe1 from a1). This also explains the choice of key move, because the wR must be on a dark square, and 1.Rg1? would prevent the wS from capturing from g1. A pretty good problem for a Commendation!
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(3) Posted by shankar ram [Sunday, May 14, 2017 06:01]; edited by shankar ram [17-05-14]

Something similar...
8 Black special knights on the squares of a Camel wheel:
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(4) Posted by Geoff Foster [Sunday, May 14, 2017 06:17]

Gyorgy Bakcsi & Laszlo Zoltan
Rochade Europa 2009
(= 4+13 )

1.Qxc4 2.Qxc6 3.Qxd7 4.Qxf7 5.Qxg6 6.Qxg4 7.Qxf3 8.Qxd3 9.Ke5 10.Qd4+ Rc5#
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(5) Posted by Nikola Predrag [Sunday, May 14, 2017 13:41]; edited by Nikola Predrag [17-05-14]

Frantisek Sabol, Commended, feenschach 2001

The threat is removing bR from b2 by 2.Bh6-c1xb2 and wB checks Bb2-c1-a3. It is checkmate because no black piece can move to c1.
Therefore wPc3 is not only redundant, but it prevents the try 1.Rc3? Re1!.
1.Rg1? Re1! ruins the logic unity of multi-refutations 1...Rf3/h3/e2 +
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(6) Posted by René J. Millour [Thursday, May 18, 2017 06:45]

Champagne TT, WCCC Rhodes, 2007
1st Prize
(= 11+3 )

ALICE A (3+2) B (8+1)


ALICE ==> The pieces have two states, A and B. At the beginning, all the pieces are in state A. When a unit moves, it changes to B, on its second move it returns to A, on its third move back to B, ... The change of state takes place at the conclusion of the move. Interferences and captures only occur between pieces in the same state, but the positions of the Kings must be legal – as if in orthodox chess – both before and after the change in state. Here on the diagram, the upside down pieces are not Nightriders, but orthodox Knights in Alice B state!

A on light squares and B on dark squares, the S coming from b1 is not on the board! 9 wSs are present, one of them comes from g1, and the others are inevitably 8 promoted Ps! It means
- a8B+ cannot be the last move,
- Black could not capture e.p.,
- each Excelsior may contain an e.p., theoretically White could make 8 e.p. captures!

But the wPs may not use the double-step in order to be in B state on 5th rank as needed to capture e.p., implying 8 Excelsiors in 6 moves, with 8 Ss born in A state!
On the diagram, the wSs are A on dark squares and B on light squares, meaning that 8 Ss were born on dark squares!
Consequently, we have 4 Excelsiors with simply an e.p. capture (for example a2...a5xb6e.p.-b7-b8S), and 4 Excelsiors with an e.p. capture + an extra capture in order to end on a dark square (for example b2...b5xa6e.p.-a7xXb8S or b2...b5xa6e.p.xXb7-b8S).

The last move was necessarily Bc6xYa8+. An uncapture is needed, otherwise Black would be retro-stalemated: Se3 and Bh3 have no retro-moves and, in B state on c6, the wB retro-paralyses the bK (retracting a move like Ka6-b7 is illegal, in the forward play the K would have placed himself in check in B state before turning to A). Y is neither a B (already on h3), nor a S: in B state on a8, this S would retract A on c7 with retro-check! Y is Q or R.
It seems all is OK for 8 e.p. captures, the 4 black extra victims being R+R+B+S or Q+R+B+S?!... Mind the trap!

Look again at our example: b2...b5xa6e.p.-a7xXb8S or b2...b5xa6e.p.xXb7-b8S. Se3 comes from g8. The missing bS is A on dark squares, but it cannot be taken on b8 because the P is in B state on a7. The same S can be in B state on b7, but the P is A on a6! Finally, only 3 extra captures are available, and consequently 1 e.p. capture could not take place. For example after a2...a5xb6e.p.-b7-b8S, [Pb2] simply plays the quiet Excelsior b2...b8S (not using the double-step, this is very important!), [Pa7] is not captured e.p., and [Pa7] itself cannot capture e.p. as 8 wPs are promoted! The answer is:

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(7) Posted by Andrew Buchanan [Wednesday, Apr 20, 2022 00:14]

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(8) Posted by edderiofer [Wednesday, Apr 20, 2022 08:39]

I had this exact thought the other day, but Andrew's deleted post alerted me to the existence of this thread. Spurred on by this thread, I've composed the following mate in 2:

(= 9+4 )

Sophie Y. He, #2vvvvvvv

I'm sure the setting could be improved further (there are so many second-move duals, and the key is flight-taking), but I like the economy of pieces here (outside of the required eight white knights of course).
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(9) Posted by Hauke Reddmann [Wednesday, Apr 20, 2022 09:32]

Very nice! It took me a whopping five seconds
to check which knights must stay put.

EDIT: One could try to put as many defense burden on
a single black piece as possible (even if this increases
the number of lame checking defenses):
e.g. bQb4 bPc2 instead of bBb4 bSc4.
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MatPlus.Net Forum General Extreeeeme Knight Wheel