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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 do not need to occur in succession. The idea behind the rule is that if the position occurs 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. ==The rule== The relevant rule in the FIDE laws of chess is 9.2, which reads: :The game is drawn, upon a correct claim by the player having the move, when the same position, for at least the third time (not necessarily by sequential repetition of moves) ::a. is about to appear, if he first writes his move on his scoresheet and declares to the arbiter his intention to make this move, or ::b. has just appeared, and the player claiming the draw has the move. :Positions as in (a) and (b) are considered the same, if the same player has the move, pieces of the same kind and color occupy the same squares, and the possible moves of all the pieces of both players are the same. :Positions are not (to be ) the same if a pawn that could have been captured en passant can no longer be captured or if the right to castle has been changed. While the rule does not require that the position occur three times on nearly ''consecutive'' moves, it happens this way very often in practice, typically with one of the kings being put into perpetual check. The intermediate positions and moves do not matter – they can be the same or different. The rule applies to ''positions'', not ''moves''. If the claim for a draw is incorrect, the opponent is awarded an extra two minutes and the game continues.〔(FIDE Laws of Chess ), article 9.5.b〕 Unreasonable claims may be penalized pursuant to article 12.6 which forbids distracting or annoying the opponent. Even if the claim is incorrect, any draw claim is also a draw offer that the opponent may accept.〔(FIDE Laws of Chess ), article 9.1.b.3〕 Draws by this method used to be uncommon . 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「threefold repetition」の詳細全文を読む スポンサード リンク
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