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Promotion is a chess rule that a pawn that reaches its eighth rank is immediately changed into the player's choice of a queen, knight, rook, or bishop of the same color. The new piece replaces the pawn on the same square, as part of the same move. The choice of new piece is not limited to pieces that have already been captured; it is legal for promotion to result in a player controlling, for example, two Queens of the same color despite starting the game with one. Promotion is immediate and mandatory for any pawn that reaches its eighth rank, and the pawn may not remain a pawn. Pawn promotion, or the threat of it, often decides the result of a chess endgame. Since the queen is the most powerful piece, the vast majority of promotions are to a queen. Promotion to a queen is often referred to as queening. A promotion to a piece other than a queen is called underpromotion . If the promoted piece is not physically available, FIDE rules state that the player should stop the game clock and summon the arbiter for the correct piece. Under US Chess Federation rules and in casual play, an upside-down rook may be used to designate a queen . ==Promotion to various pieces== Promotion to a queen is the most common, since the queen is the most powerful piece. Underpromotion (promotion to a piece other than a queen) occurs more often in chess problems than in practical play. In practical play, underpromotions are rare, but not extraordinarily so (see table below).〔''Learn Chess'', by John Nunn, p. 33 says that over 99% of promotions are to the queen〕 As the most powerful piece, the queen is usually the most desirable, but promotion to a different piece can be advantageous in certain situations. A promotion to knight is occasionally useful, particularly if the knight can give immediate check. A promotion to a rook is occasionally necessary to avoid a draw by immediate stalemate that would occur if the promotion was to a queen. Promotion to a bishop almost never occurs in practical play (about one game in 33,000). (See Underpromotion: Promotion to rook or bishop for examples of underpromotions to rook and bishop made in order to avoid stalemate.) The percentage of games with promotions can be misleading, because usually a player resigns when they see that they cannot stop their opponent from promoting a pawn. In the 2006 ChessBase database of 3,200,000 games (many at grandmaster or master level), about 1.5% of the games include a promotion. In these games (counting only once the games in which the same player promotes more than one pawn to the same piece) the proportions of promotions to each piece are approximately: : This suggests that about 3% of all promotions are underpromotions. The frequency of truly significant underpromotions is, however, less than this. Note that the promoted piece does ''not'' have to be a piece that has previously been captured. A player may promote to any piece they wish, regardless of whether or not such a piece has been captured. In theory, a player could have nine queens, ten knights, ten bishops or ten rooks, though these are highly improbable scenarios. Some chess sets come with an extra queen of each color to use for promoted pawns.〔(USCF Learn to Play Chess )〕 If an extra queen is unavailable, it is often represented by an upside-down rook instead.〔"It is common practice, however, to play using an upside-down rook for a second queen. In the absence of a player's announcement to the contrary, an upside-down rook will be considered a queen.", Just & Burg, p. 17〕 The diagram from the game between Bobby Fischer and Tigran Petrosian in the 1959 Candidates Tournament shows a position in which each side has two queens. Four queens existed from move 37 until move 44 . Very few games are played with six queens, two examples are Emil Szalanczy vs. Nguyen Thi Mai (2009) and David Antón Guijarro vs. Alejandro Franco Alonso (2011). In the first game each side had three queens after 58th move until 65th move.〔 The game ended in a draw with a single queen on each side.〔 In the second game both sides also had three queens, but Black ultimately resigned, with a single queen on both sides.〔 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「Promotion (chess)」の詳細全文を読む スポンサード リンク
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