Monday, August 11, 2008

Circe (1)

One amazingly interesting condition of the Fairy chess is Circe Chess. There are many kinds of this condition. In the following we describe some of these kinds, ten kinds of Circe and one Anti-Circe, and we present an example of the first kind, the regular Circe.

1. Regular Circe : A captured piece is instantly reborn on the initial- game- square. (We name “initial- game- square” the square which is used for the initial placement of the piece when we start a classical chess game. For example, the white-squared white Bishop has f1 as initial- game- square).
If the initial- game- square is occupied, then the captured piece is out of the game (is lost).
If the captured piece is one of those which move on squares of various colors (i.e. R, S), then the piece is reborn on an initial- game- square with same colour as the capture- square. (For example a white Rook, if it is captured on the white c8 it will be reborn on the white h1, but if it is captured on the black d8 it will be reborn on the black a1).
If a Pawn is captured, it will be reborn on the initial- game- square of the same file where the capture- square is. (The initial- game- square of a white Pawn is on row-2, while the initial- game- square of a black Pawn is on row-7).
The Circe condition is not applied on the King.
Castling with a reborn Rook is allowed.
The fairy pieces (which we believe that appeared after a strange Pawn promotion) are reborn on the promotion- square of the capture- file. (We know that the promotion happens on row-8 for white pieces and on row-1 for black pieces).

2. Circe Parrain : The square, where the captured piece-A will be reborn, is specified after the move of the next same-colored piece-B. The line from the capture- square to the regeneration- square is parallel, equal in length, and has the same direction with the move of piece-B. In other words, the piece-B by making its move specifies the name of the square for regeneration of piece-A (becomes the godfather, “parrain” in French).
The Pawns can be reborn on row-1 and on row-8. It it is promotion- row for them, they are instantly promoted to any piece the owner of the Pawn desires. If the row is not promotion- row, they can make (in a later move) a step on the file.

3. Circe Rex Inclusiv : It is like the regular Circe, but the Circe condition is valid for the Kings, that is the King can be captured and reborn on its initial- game- square. (If the square is occupied, it is the end of the game).

4. Diagram Circe : It is like the regular Circe, but the captured piece is reborn on the initial- diagram- square. (We name “initial- diagram- square” the square on which the captured piece was placed in the initial position of the problem).

5. Interchange Circe (German “Platzwechsel-Circe”, PWC) : It is like the regular Circe, but the captured piece is reborn on the departure- square of the capturing piece. Capturing piece and captured piece interchange places.

6. Kamikaze Circe : It is like the regular Circe, but additionally the capturing piece is also reborn.

7. Mirror Circe : It is like the regular Circe, but the captured piece is reborn as if it were of the opposite colour.

8. Reflecting Circe : The regeneration- square is symmetrical (with axis of symmetry the line between file-d and file-f) with the one that would be valid in regular Circe.

9. Symmetrical Circe : The regeneration- square is symmetrical (with center of symmetry the center of the chess-board) with the square of the capture. (Capture on g6, regeneration on b3).

10. Volcanic Circe : The captured piece is not out of the game when the regeneration square is occupied. The piece remains inactive “in” the square. Just as the square is evacuated, the captured piece reappears there having all its power.

11. Anti-Circe : On making a capture, the captured piece is lost and the capturing piece is reborn on its initial- game- square, but if it cannot be regenerated there the capture is forbidden.
A piece standing on its initial- game- square can make a capture remaining practically motionless!
A Pawn can capture with simultaneous promotion, if the regeneration- square of the promoted piece is unoccupied.

Regular Circe, with multiple promotions

Now we will study the problem-201, by N. A. Macleod, with theme AUW and condition Circe, (which problem is the enlightening example on the web-page of British Chess Problem Society after following the link “Fairy Chess”).
On writing the solution of a Circe problem, after each capture move, we note inside a parenthesis that a piece is added, (i.e. (bBc8) means that a black Bishop is added on square c8).

(Problem 201)
N. A. Macleod
First Honourable Mention, Europe Echecs 1977
Mate in 2 moves. Circe.
#2 Circe (10+4)

The problem has various tries :
{1.Sg1+? / Sxd2+? / Sh2+? / Sh4+? / Sg5+? / Sxd4+? Bd5!}, and we understand that it is of no use to lift the Knight Sf3 and check by discovery of the Bishop Bh1, because the black Bishop Ba2 can be interposed on d5, and if it is captured there by the wB giving check (2.Bh1xd5(+bBc8)+), the bB is reborn on c8 and can be interposed again on b7! As it seems we are out of moves since the problem is a two-mover. But suppose we insisted with (3.Bd5xb7(+bBc8)+), then the bB would be reborn on c8 and it would capture the wB (3...Bc8xb7(+wBf1)).
{1.Qe4+? Bd5!}, similar comment, as with previous tries.
{1.b3? Bxb3(+wPb2)!}.
{1.Qxd2? [2.Qa5#] Bc4!},
{1.Ra7+? Kxa7(+wRa1)!}, because during this Phase the Ra7 is unsupported.

Key : 1.Kb4! (zz). The key is not threatening something, (basically the file-a is evacuated), and is bringing Black into a zugzwang situation. If the wRe1 is captured, it will be reborn on a1 and will pin the bBa2, (and then the wSf3 will be lifted to discover wBh1, which will check-mate).

1...dxe1=Q(+wRa1)+ 2.Sxe1(+bQd8)#

1...dxe1=R(+wRa1). White cannot continue with (2.Sxe1(+bRh8)+? Rxh1(+wBf1)!), so White plays (2.Sg1#) and bRe1 is blocked.

1...dxe1=B(+wRa1)+. Here the move (2.Sxe1(+bBf8)+) is forbidden since the bB is reborn on a square where it continues to check. The correct continuation is (2.Sd2#) and bBe1 is unable to interfere.

1...dxe1=S(+wRa1), and bSe1 can interfere on the main diagonal. White is futile to continue with (2.Sxe1(+bSb8)+?), since the bS is reborn on a square from which it can again interfere on the main diagonal. The correct continuation is (2.Qe4#).

The problem has achieved the four promotions (theme Allumwandlung, AUW).
In the next variation we see a peculiarity of the Circe condition, namely that a piece can support itself!

1...B~ 2.Ra7#. Now that bB has evacuated file-a, the defense (2...Kxa7(+wRa1)?) is forbidden since wR is reborn on a1 and guards a7. That is, during the Phase of the actual play the white Rook supports itself from a great distance and from the future! We see now why the white King in the key-move left file-a!

(This post in Greek language).

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