Threefold Repetition

In chess and some other abstract strategy games, the threefold repetition rule (also known as repetition of position) states that a player can claim a draw if the same position occurs three times, or will occur after their next move, with the same player to move. The repeated positions need not occur in succession. The idea behind the rule is that if the position is repeated three times, no progress is being made.

In chess, in order for a position to be considered the same, each player must have the same set of legal moves each time, including the possible rights to castle and capture en passant. Positions are considered the same if the same type of piece is on a given square. So, for instance, if a player has two knights and the knights are on the same squares, it does not matter if the positions of the two knights have been exchanged. The game is not automatically drawn if a position occurs for the third time – one of the players, on their move turn, must claim the draw with the arbiter.

In shogi, a fourfold repetition (千日手 sennichite) is required to end in a draw. Each player must have the same pieces in hand as well as the same position on the board. The result is a draw unless one player is giving perpetual check; in that case, that player loses.