Chess960

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Chess960, (or Fischer Random Chess)
a chess variant invented by former World Chess Champion Bobby Fischer, introduced on June 19, 1996 in Buenos Aires, Argentina [1] . Randomizing the pieces on its back rank has been known as Shuffle Chess, but Chess960 introduces rules so that castling options are retained in all starting positions, one player's bishops must start on opposite-color squares, and the king must start on a square between the rooks, resulting in 960 unique positions, while the classical initial position is one of them. Chess960 practically handicaps the application of opening theory in classical chess with the memorization of opening moves, both for human as well for chess programs.

Castling moves with chess GUIs

For chess, players make a castling move by moving their Kings to two cells, left or right. However, for Chess960 sometimes they can’t move their King to two cells since the target cell may be still occupied by a piece and/or the distance between the King and the target cell may vary from 1 to 6 (not only 2 cells). Many chess GUIs solved that difficulty/ambiguity by changing the way to make castling move: move the King to capture its own Rooks.

Programming

Chess960 is almost identical to chess, except for initial positions and the castling rule. A chess software can easily support Chess960 with only a few changes.

Initial positions

A typical chess engine can support any given position thus it can parse correctly any initial position. It needs to parse input, setup, and process correctly the castling statuses.

For other software such as chess GUIs which need to generate all initial positions, they can simply store all initial FENs or use some algorithms to generate them when needed.

Notations

Chess960 can use all chess notations with some caring about ambiguities:

  • Some chess GUIs send castling moves as O-O, O-O-O (e.g., Arena) when some other ones send as own-Rook captures (e.g., Shredder GUI, WinBoard, Banksia GUI) such as d1e1.
  • Variant name (in PGN file): some programs use the name “Fischerandom” but others may use “Chess960”
  • UCI engines: some engines tell chess GUIs that they support Chess960 via the option UCI_variant, others via UCI_Chess960

See also

Publications

Forum Posts

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External Links

References

  1. ↑ The birth of Fischer Random Chess by Eric van Reem

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