## Monday, June 09, 2008

### Fairy chess

In Fairy chess belonged (in the beginning of the twentieth century) all the heterodox types of problems. When the helpmates and the selfmates became common enough, they were still heterodox but stopped being considered as part of the fairy genre of chess.
Today inside the realm of fairy chess remain the problems (a) with fairy pieces, (b) with fairy conditions, (c) with fairy chess boards, (d) with retroanalysis, (e) with constructive tasks.
Some fairy problems have excellent ideas in them and it is a pity that the fairy type is not widely known. The advanced solvers find great pleasure studying the solutions of the fairies.
The fairy problem composers have smaller risk that their creation will be anticipated.

(a) Pieces
The basic pieces are six : K Q R B S P . The fairy pieces are more than a thousand. Some pieces are interesting and are being used by many composers, some other pieces are just curious proposals. The fairy pieces are different from the basic in the way of movement or some other property, and they extend the possibilities of the problemists in new unexplored areas.
Trying to divide the pieces in categories, we find three basic categories, (Leapers, Riders, Hoppers), but there exist some pieces not belonging to any of those three.

First category, we have the leapers, pieces which move from a square to a certain distance, without being hindered by intermediate pieces. When a leaper is giving check we cannot intercept it.
In this category we already know the Knight. If we suppose that the Knight is in the center of a square having side equal to [1], then it can jump to the center of a square at a distance [square root of 5].
We can specify with two numbers (r,c) how many squares on the row and how many squares on the column the leaper can move. Sometimes the move with capture may be different from the move without capture.
S: The Knight is leaper (2,1) or (1,2) and with each step goes to a differently colored square.
C: The Camel is leaper (3,1) or (1,3) and stays on same colored squares.
Z: The Zebra is (3,2) or (2,3) and goes to a differently colored square.
K: The King is a hybrid leaper (1,0) or (1,1).

Second category, we have the riders, which have linear move and are hindered from intermediate pieces. With riders we create pins and interceptions.
We can specify with two numbers (r,c) how many squares on the row and how many squares on the column each step of the rider is. The riders are multi-stepping leapers. Sometimes the move with capture may be different from the move without capture.
B: The Bishop is rider (1,1) and stays on same-colored squares.
R: The Rook is rider (1,0) or (0,1).
Q: The Queen is a hybrid rider (1,1) or (1,0).
P: The Pawn moves as rider (0,1) or (0,2) and captures as rider (1,1), always going away from its initial square.
N: The Nightrider is rider (2,1) or (1,2).

Third category, there are the hoppers, which can move only if an intermediate piece exists, over which they hop. This intermediate obstacle can also be called "a hurdle".
G: The Grasshopper moves like the Queen and steps just behind the hurdle, where it can capture an opponent piece. (The Rook in castling makes a move like a Grasshopper).
L: The Locust moves almost like the Grasshopper, but captures the hurdle and steps to any square after the hurdle, if the line is open.

Of great interest are the composite pieces. We already know the Queen, which moves and captures like Rook or Bishop. There is also the Empress combining properties of Rook and Knight, and the Princess combining properties of Bishop and Knight. Another way of combining properties can produce pieces like, QS which moves like a Queen but captures like a Knight, RS which moves like a Rook but captures like a Knight, BS which moves like a Bishop but captures like a Knight, etc..

From the Chinese chess (xiangqi) come Mao, Vao, Pao and Leo.
M: The Mao moves like a Knight but it is not a leaper. It moves, going away from its position, making a step like Rook and then a step like Bishop. If the square of the first step is occupied, the Mao cannot move.
V, P, Le: The Vao, Pao, Leo move respectively like Bishop, Rook, Queen. The difference is that when they are going to capture, they are hoppers (must hop over a hurdle).

Royal piece is the one which must not be lost, because this loss is ending the game. In normal chess there is only one, the King. In fairy chess, more than one royal pieces can coexist having the same color. If a Knight is specified to be royal piece, it will move or capture as Knight, but it will accept checks and will be in endangered as a King.

(b) Fairy conditions
Fairy conditions are continuously invented. Some conditions hold the interest of the composers only for a short time. Some other conditions, as Circe or Madrasi, are very often appearing in composition contests (and we will see more of these conditions in future posts).

In Circe chess, every captured piece is reborn on its initial square. If the square is occupied, the piece is lost. For example, initial square for a white Rook is a1 or h1. If the Rook is captured on a white square, it will be reborn on h1. If the Rook is captured on a black square, it will be reborn on a1. Similar rules are valid for Bishop and Knight. The pawn is reborn on the initial square (line-2 for white pawns, line-7 for black) of the column on which it was captured. On normal Circe the King is not included in the condition. There is another condition including the King, Circe Rex Inclusiv.
There are several variations of the Circe rules.

In Madrasi chess, if a piece threatens another piece of the same type but of different color, then both are paralyzed. The only ability left to these pieces, is to paralyze one another. In normal Madrasi the King is not included in the condition. There is another condition including the King, Madrasi Rex Inclusiv.

When the condition Series of moves is valid, (we have already seen Series helpmate), one of the two sides makes a series of moves and then the other side answers with one move to fulfill what the stipulation has specified.

(c) Fairy chessboards
The cylindrical chessboards were very popular in the beginning of the twentieth century.
An horizontal cylinder has file-h in contact with file-a.
A vertical cylinder has in row-8 in contact with row-1.
The combination of the two cylinders is called torus or anchor ring.
There are chessboards which are not square-shaped, or having another (different than 64) number of squares.
In a special category we find the three-dimensional chess (3d-chess), like the one played by Mr. Spock in the TV series "Star Trek".

(d) Retroanalysis
In the category of retroanalysis (or retro) belong the problems, for which we need to discover what had happened in previous moves. We may seek the sequence of moves which led to the given position, as in the proof games, or we may wish to prove that an option is valid (for example, castling) for one or both opponents.