RULE CHANGES IN CHESS
There have been no recent changes to the moves of the pieces, but the wording of some rules were changed. Publicity (e.g. by chess problem setters) showed that the old wording of two rules allowed unintended types of moves:
- The promotion rule was found to say that a pawn is to be promoted to "a piece" of unspecified color, thus including an enemy piece (thus on occasion blocking the enemy king in, or preventing stalemate by giving the opponent something to move).
- The castling rule was found to allow (White) Ke1–e3 and Re8–e2, and (Black) Ke8–e6 and Re1–e7, if "the rook had not been moved" as a rook because it had been a pawn underpromoted on e8/e1.
The wording of both rules was changed to forbid the unintended allowed moves.
In recent times, more ways to lose have been brought in:
- The 1851 London Chess tournament showed the need for time control, resulting in ability to "lose on time".
- A player whose mobile phone rings during a game, thereby loses; but if the other player cannot win by any possible sequence of legal moves, the result is a draw.