Fifty-move rule
The 50 - move rule in chess states that a game as a draw ( a tie ) is to be considered if one of the players can prove that the last 50 consecutive of each player moves have beaten a stone without that or a pawn been.
Practical significance
The 50-move rule is to prevent endless back and strutting about on the chessboard without permanent changes in the position of the image. A chess position can be irreversibly changed only when
- A farmer prefers
- A stone is captured
- Lost future rights to one or both reshuffles the origin field by first-time drawing of a tower or the king,
- Or after the double move of a pawn en passant one is possible.
The game is not automatically a draw after 50 moves, but the draw must be claimed by a player. According to the Laws of Chess FIDE this can only be the player who is on the train. This is one of the reasons for the notation duty at tournament games. It is quite possible that a game will be continued beyond the point at which draw can be claimed for the first time. In theory, can go on forever a game according to the rules, but in practice, at least one of the two players will be interested usually to be able to claim a draw.
The roots of the 50 - move rule to the 16th century. A text of Ruy López de Segura about chess from 1561 already contains details about them. The number of 50 trains was originally scheduled, because in the final bishop, knight, king against king in the worst starting position for perfect play from both sides 33 trains are required to Matt.
In the 1980s it was discovered with the help of endgame databases that some endings can only be obtained with more than 50 trains or only from certain positions out. Examples are bishop pair and king and knight and king or certain positions in which rook and bishop are fighting against a tower. The rule was supplemented by FIDE in December 1984 to exceptions that 100 trains allowed for certain distributions of material, especially in the endgame rook and bishop against rook. After protests of many Grandmaster FIDE reduced this number first on 75 All of these exceptions have been deleted again on 1 January 1993, since all material combinations are again the 50 - move rule.
Rare games are already terminated before reaching the final by the 50 - move rule. An example is the game Filipowicz - Smederevac of 1966, which ended after the 70th train without a single figure had been beaten - the last farmer was pulled in the 20th train. In 2005 ended a game between Pouw and Van Dort after 69 train draw by the 50 move rule. Although it was defeated, however, found after 19 train neither shock nor pawn moves instead.
Chess Mathematics
There are extensive studies - the first time in 1911 by TR Dawson - how many trains a chess game can consist of a maximum if the players cooperate in the construction of the longest possible match, but each player complains draw after 50 moves rule as soon as possible. There are 5899 trains.
There are in a game of chess more than 30 impact and maximum 6 * 16 = 96 pawn moves. Thus, focusing on each of the eight lines in pairs standing against white and black farmers " past each other ," may each be employed, either the white or the black pawn of each pair make a capture. Thus, at most 30 96-8 = 118 periods without farmers or capturing move possible.
If the player who made the last captures are farmers or prior to such period also makes the next farmers or capturing move, it can be made between most 99 half moves without farmers or capturing move. In contrast, when alternating black and white in it, impact or to make a pawn as the next, so in between can only exceed 98 half moves without farmers and captures are made . There are at least three such change necessary:
Black begins. He suggests one or both white knight, and provides the farmers on suitable ( first change, see diagram ), then makes white seven and six other Bauenschlagzüge and converts the farmers around (second change), then the remaining beats black white figures with except for the white king and converts the farmers around (third change), then the remaining beats white black figures with the exception of the black king.
Thus, the number of half moves at most ( 118-3 ) * 100 3 * 99 = 11797th Therefore, the game with the 5899th train of white must end.
In practice such long games do not occur. Well known is the match between Thomas Ristoja and Jan -Michael Nykopp 1971 ( Open Championship of Finland ), as it was agreed by 300 trains and nearly 15 hours of play for a draw.
A game in which the 50 - move rule was in force from the beginning and was never offered in the chess, ends after the maximum number of possible moves to the position Kh1, Ka8. What was the last train?
Solution: 5899.Kg2xTh1 A black knight or bishop would be dead because position is not sufficient. A lady would offer chess, but this was ruled out. For the same reason the king must have come also from g2. The number of moves resulting from the calculations of the longest match.