Fairy chess piece
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Princess (knight+bishop compound) |
|---|---|
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Empress (knight+rook compound) |
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Grasshopper (shown as an inverted queen) |
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Nightrider, knightmare, or unicorn (shown as an inverted knight) |
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Berolina pawn or sergeant (shown as an inverted pawn) |
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Ferz (shown as an inverted bishop) |
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Wazir (shown as an inverted rook) |
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Mann (shown as an inverted king) |
A fairy chess piece or unorthodox chess piece is a chess piece not used in conventional chess but incorporated into certain chess variants and some chess problems. Fairy pieces vary in the way they move.
Because of the distributed and uncoordinated nature of unorthodox chess development, the same piece can have different names and different pieces the same name in various contexts.
Fairy chess pieces usually fall into one of three classes, although some are hybrids. Compound pieces combine the movement powers of two or more different pieces.
A specialized solving program, WinChloe, recognizes more than 1200 different fairy pieces.
An (m,n)-leaper is a piece that moves by a fixed type of vector between its start square and its arrival square. One of the coordinates of the vector 'start square – arrival square' must have an absolute value equal to m and the other one an absolute value equal to n. A leaper moves in the same way whether or not it captures, the taken unit being on the arrival square. For instance, the knight is the (1,2)-leaper.
The leaper's move cannot be blocked; it "leaps" over any intervening pieces, like the knight in standard chess.
It is convenient to classify all fixed-distance moves as leaps, including (1,0) and (1,1) moves to adjacent squares, because that allows all normal chess moves to be placed in two categories (leapers and riders) without the need to create a third category to describe the king and pawn.
In shatranj, a Persian forerunner to chess, the pieces later replaced by the bishop and queen were also leapers: the alfil was a (2,2)-leaper (moving exactly two squares diagonally in any direction), and the fers or ferz a (1,1)-leaper (moving exactly one square diagonally in any direction). The wazir is a (1,0)-leaper (an "orthogonal" one-square leaper). The king of standard chess combines the ferz and wazir.
The dabbaba is a (2,0)-leaper. The alibaba combines the dabbaba and alfil, while the squirrel can move to any square 2 units away (combining the knight and alibaba). The Arabic word formerly meant a type of medieval siege engine, and nowadays means "army tank".
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Wikipedia