No.976,977 (CJF)

No.976, 977
Chris Feather (England)


Original Problems, Julia’s Fairies – 2015 (II): July – December

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No.976, 977 by Chris Feather – Isardam specific mate positions reached with a help of Equipollents Circe. (JV)


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. Castling with replaced Rook is permitted. Pawns may be reborn on the 1st and 8th ranks. Pawns reborn on the 8th rank are promoted as part of rebirth and the promotion is chosen by the player who makes the capture, i.e., if White captures a black Pawn, and the black Pawn is reborn on the 8th rank, White (not Black) decides what Black’s Pawn will be promoted to. Pawns reborn on the 1st or 8th rank can make only one-square move (for example black Pc8 can play only on c7 or it can capture an enemy units on ‘b7’ or ‘d7’). During the en passant capture, the Pawn is replaced on the rank opposite of the captor. For example, if Black moves c7-c5, White Pawn on ‘b5’ captures en passant, moves to ‘c6’, while the black Pawn is reborn on ‘d6’.
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

original – 19.12.2015

Solutions: (click to show/hide)

white Kc4 black Kf4 neutral Pd3f3

h#3.5*                                (1+1+2n)
Circe Equipollents

No.977 Chris Feather

original – 19.12.2015

Solutions: (click to show/hide)

white Kd4 black Kh1 neutral Pe3e4

h#3.5              duplex         (1+1+2n)
Circe Equipollents

5 Responses to No.976,977 (CJF)

  1. Geoff Foster says:

    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)!

  2. Geoff Foster says:

    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.

    • Eric HuberEric Huber says:

      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.

    • Seetharamanseetharaman says:

      Strange that Chris Feather missed this.

      • Geoff Foster says:

        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!

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