Transformation (chess)
A conversion or pawn conversion in chess occurs when a pawn reaches the opponent's back rank. As part of this move, the pawn is immediately to be replaced by another chess piece of the same color with the exception of the king , i.e. by a queen (usually), a rook , a bishop or a knight . The converted figure is effective immediately.
Importance in the game of chess
In the opening there are almost no conversions because the pawns are still too far away from the opposing back row and are easy to stop. However, there are a few opening traps where conversion does play a role, such as: B. in Albin's counter-gambit . In the middle game are transformations rather rare. In the endgame, however, the transformation becomes the dominant theme, as the material is usually no longer sufficient to force a mate without it. The position evaluation is then essentially reduced to the question of which of the two players can convert a pawn first. To do this, a passed pawn must first be formed. If one player succeeds in doing this, the other's goal must be to stop the passed pawn and prevent it from converting. The control of the transformation field is of particular importance. (More on this in the articles on pawn endings , rook endings , etc.) Since the material balance is extremely shifted by the conversion, many players give up the game as soon as they realize that they can no longer prevent the conversion of a pawn.
Usually it is converted into a lady because she is the strongest figure. If the pawn is transformed into another, inferior figure, for example to give a knight's fork , one speaks of sub-transformation . It seldom makes sense to turn a pawn into a rook or a bishop, since a queen can make all the moves of both a rook and a bishop. However, in some situations such a conversion can prevent the opponent from stalemating .
Tournament practice
Candidates Tournament 1959
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When a pawn reaches the opponent's back row, it must be replaced immediately by the desired piece. Since the selection is not limited to pieces that have already been captured, a player can, for example, come into possession of two or more queens. The record in a practical game is six queens on the board, although fake games with up to seven queens also exist. There were also games with five rooks and five knights.
In practice, the problem sometimes arises that the desired figure (e.g. a second lady) is not tangible. In this case, the rules require that the referee or chief of competition interrupt the game by stopping the chess clock. If the referee is not nearby, the player himself may stop the chess clock to call the referee for help (FIDE rule 6.12).
Especially in free blitz games , it is sometimes tolerated if an upside-down rook is used as an additional queen. However, this is not compliant with the rules. This played e.g. B. at the Canadian Championship 2017 a role. In the decisive blitz game in the play-off for the title, Nikolay Noritsyn could not find a lady for the conversion in a time shortage. Instead of stopping the clock and asking the referee for a queen, he placed an inverted rook on the conversion square. The referee declared the move to be correct but insisted that the conversion figure was a tower. This decided both the game and the Canadian Championship for his opponent Bator Sambuev.
Historical
In the Arabic Shatrandsch , a pawn who had reached the opposing back row was converted into the weakest piece, the Firzan . In the Middle Ages, the transformation into a queen was only possible if the original queen had already been taken off the board. This rule lasted until the 17th century. From 1560 sub-metamorphoses were also allowed, although the rules were not uniform for a long time.
As recently as around 1840, the rule in German-speaking countries was that a pawn was only allowed to transform into a piece that had previously been defeated and thus taken off the board. This could lead to fundamental difficulties, as the Swiss Johann Conrad von Orelli (1788-1854) showed in his chess booklet in 1840 .
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No white piece has yet been captured , which is why the pawn on a8 cannot convert according to the above rule. White therefore has to wait until one of his pieces is captured before he can exchange that piece on a8 for the pawn. A problem arises when White draws Qd3 – e4 + . After Qe7xe4 + , the captured white queen would be replaced on a8 and Black would be instantly mate. On the other hand, the white king would also be in check with the queen. The question of what now has priority and how this problem could be resolved ultimately remained unanswered.
In the second half of the 19th century it was also allowed not to convert the pawn after reaching the opposing back row , but to leave it as a pawn on the transformation field until the end of the game - see dummy pawn .
Special features of the conversion rule
White to move could mate in one move, and conversion to an opposing piece would be legal.
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White moves g7 – g8D in accordance with the rules , then the black king captures on g8 on the next move and mate takes a few more moves (e.g. after Rf6 or Ne5).
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White moves g7 – g8 and illegally converts to a black knight, then Black is immediately mated.
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FIDE rule 3.7.e states:
“As soon as a pawn has reached the row furthest from its original square, it must be exchanged as part of the same move for a queen, a rook, a bishop or a knight of the same color. The choice of the player is not limited to pieces already captured. This exchange of a pawn for another piece is called a 'conversion' and the new piece takes effect immediately. "
The express condition of converting to a piece of the same color precludes converting the pawn into an opposing piece if this would be opportune in a situation. In the diagram shown, White could convert the pawn into a black knight after g7 – g8 and thereby checkmate the black king in the same move.
Web links
- FIDE chess rules. At: Schachbund.de.
Individual evidence
- ↑ Game to replay on chessgames.com , accessed on November 15, 2018
- ^ Tim Krabbé : Chess records.
- ↑ Mike Kline: Explosive end at the Canadian Championship. At: Chess.com. July 4, 2017, accessed March 18, 2018.