No.976, 977 |
Original Problems, Julia’s Fairies – 2015 (II): July – December →Previous ; →Next ; →List 2015(II) Please send your original fairy problems to: julia@juliasfairies.com |
No.976, 977 by Chris Feather – Isardam specific mate positions reached with a help of Equipollents Circe. (JV)
Definitions:
Circe Equipollents: After a piece is captured, it is immediately replaced on the square which is the same distance and direction from the square of its capture, as was that square from the square upon which its captor commenced its move. (If Qf7 captures a Pawn on e7, it is reborn on d7, because d7 is a same distance and direction from e7 as e7 is from f7. Similarly, if Qg7 captures a piece on ‘e7’ its rebirth square is ‘c7’). If the rebirth square is occupied the captured piece disappears
OR from Fairings No.46:
Equipollent Circe: After a capture the captured piece is reborn on a square defined with respect to the square where it stood before its capture, as follows: The rebirth square lies in the same direction as that of the capturing move and at a distance equal to the length of that move. If the rebirth square is occupied or would be off the board the capture is normal. [“Equipollent” simply means “equivalent”.]
Isardam: Any move, including capture of the King, is Isardam illegal if a Madrasi-type paralysis would result from it.
Madrasi: Units, other than Kings, are paralysed when they attack each other. Paralysed units cannot move, capture or give check, their only power being that of causing paralysis.
No.976 Chris Feather |
Solutions: (click to show/hide) |
white Kc4
black Kf4
neutral Pd3f3
h#3.5* (1+1+2n) |
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No.977 Chris Feather |
Solutions: (click to show/hide) |
white Kd4
black Kh1
neutral Pe3e4
h#3.5 duplex (1+1+2n) |
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In 976, Black answers a check from a Rook by also promoting to Rook, so that two pieces of the same type attack the black King. The white King then mates by pushing one of the Rooks behind the black King, creating an Isardam “spike” in which the black King cannot move.
977 has a different method of setting up the Isardam spike: a Rook or Bishop on the 7th rank captures the bPe4, which is reborn on the bottom rank and promotes to the same type as the capturing piece. It is strange that Popeye 4.73 does not recognise 4.nBxe4(+nPh1=nB) as a valid move, because it is exactly analogous to 4.nRxe4(+nPe1=nR). Also, Popeye recognises the move 4.nBxe4(+nPh1=nB) when there is a wP on g2 (but not with a bKg2). In the second solution note that 4…Kf2? does not work, because of 5.Kxe4(+nRe5)!
On second thoughts, the first solution of 977 is not valid. The move 4.nBxe4 is played by Black, so the neutral Pawn is white, which would not promote on the bottom rank! Some older versions of Popeye used to allow promotion, but it is a bug and was fixed in Popeye 4.73. WinChloe only gives the second solution, in agreement with Popeye 4.73.
That’s right, Geoff.
The Popeye bug appeared in version 4.62 and is present in all versions from 4.62 until 4.71.
This problem is solved correctly by Popeye 4.61 (and previous versions) and 4.73. It is a good thing to know when testing a problem featuring neutral promotions.
Strange that Chris Feather missed this.
It is easy to miss because the problem is a duplex, so 4.nBxe4(+nPh1=nB) looks just like 4.nRxe4(+nPe1=nR), but is played by a different side!