fifty move rule

 

This article uses algebraic notation to describe chess moves.

The fifty move rule in chess states that a player can claim a draw if no capture has been made and no pawn has been moved in the last fifty consecutive moves. The relevant part of the official FIDE laws of chess is rule 9.3^[1]:

The game is drawn, upon a correct claim by the player having the move, if

(a) he writes on his scoresheet, and declares to the arbiter his intention to make a move which shall result in the last 50 moves having been made by each player without the movement of any pawn and without the capture of any piece, or

(b) the last 50 consecutive moves have been made by each player without the movement of any pawn and without the capture of any piece.

Naturally, if a player writes down his next move as under (a) above, it must not be a pawn move or a capture for a valid claim. Additionally, a claim doesn't have to be made at the first opportunity – it can be made any time when there were no captures or pawn moves in the last fifty moves.

A game is not automatically declared a draw under the fifty move rule – the draw must be claimed by a player on his turn to move. Therefore a game can continue beyond a point where a draw could be claimed under the rule. Theoretically, a game could continue indefinitely under the rules though in practice, when a draw under the fifty-move rule can be claimed, one of the players is usually happy to claim it (Hooper & Whyld 1992).

Example

Karpov-Kasparov 1991
After 63. Kxh4, the last capture.   FEN 3r4/8/5N1K/3N4/8/8	After 112... Kh8.   FEN 7k/4N3B2/8/8/8/r7

A draw by the fifty move rule could have been claimed after Black's 112^th move in a 1991 game between Anatoly Karpov and Garry Kasparov, but neither player claimed it. The last capture occurred on White's 63^rd move (and the last pawn move occurred before that). By FIDE rule 9.3 part (a), White could have written his 113^th move on his scoresheet and claimed a draw (assuming that the move was not a capture or pawn move). By FIDE rule 9.3 part (b), after White's 113^th move, either player could have claimed a draw on their turn to move, without having to write down their next move. Instead, the game continued a few more moves:

113. Ng5 Ra6+

114. Kf7 Rf6+

115. ½-½^[2]

If 115. Kxf6 the position is a stalemate. If 115. Ke8 Rxf5 116. Nxf5, and the position is clearly drawn because the two knights can't force checkmate (see two knights endgame).

History

The rule has a long history, with Ruy López's 1561 text on chess including details of it. In the 20th century, with the discovery that certain endgames (see below) can only be won in more than fifty moves (without a capture or a pawn move) from certain positions, the rule was changed to include certain exceptions in which one hundred moves were allowed with particular material imbalances. The exceptions were later removed and all material combinations are now subject to the fifty move rule.

The exceptional positions (above) were:

1. Two knights versus one pawn (See Troitsky line)
2. Rook and bishop versus a rook
3. Rook and a rook pawn on its original square, versus a pawn blocking the rook pawn and a bishop on the same color as the opponent's pawn.

In 1928 FIDE enacted rules that in the rook and bishop versus rook endgame, 132 moves were allowed, since it was twice the 66 moves that were thought to be required at that time (the actual maximal number of moves needed is 59). In 1952 FIDE revised the law, requiring that players agree to an extension for these positions before the first move is made (Whitaker & Hartleb 1960). FIDE rules allowed seventy-five moves for the rook and bishop versus rook (Müller & Lamprecht 2001:299).

At some point, the rule was changed to one hundred moves for such positions. Later more positions requiring more than fifty moves were found. FIDE included these endgames in the extended rule:

1. queen versus two bishops
2. queen versus two knights
3. two bishops versus a knight
4. two knights versus a pawn
5. rook and bishop versus a rook, and
6. a queen with a pawn on the seventh rank versus a queen.

The one hundred move extension was in force for a short time, and it was changed to seventy-five moves in 1988 (Hooper & Whyld 1992). In 1992 the rule was changed back to fifty moves for all positions.

Many of the longest games on record involve the rook and bishop versus rook endgame, when the rule for more moves was in effect. ^[3]

Games drawn under the fifty move rule before the endgame are rare. One example is Filipowicz - Smederevac, Polanica Zdroj 1966, which was drawn on move 70 without any captures having been made in the whole game and with the last pawn being moved on move 20.

See also

• Rules of chess
• Threefold repetition
• draw (chess)

Notes

1. ^ FIDE Laws of Chess, October 2004
2. ^ http://www.chessgames.com/perl/chessgame?gid=1067317
3. ^ http://www.xs4all.nl/~timkr/records/#Longest%20game

The recgames.pgn file may now be downloaded from this page of Tim Krabbe's site -

http://www.xs4all.nl/~timkr/records/records.htm

References

• Hooper, David & Whyld, Kenneth (1992), The Oxford Companion to Chess (2 ed.), Oxford University Press, ISBN 0-19-866164-9
• McCrary, John (2004), "The Evolution of Special Draw Rules", Chess Life (no. November): 26-27
• Müller, Karsten & Lamprecht, Frank (2001), Fundamental Chess Endings, Gambit Publications, ISBN 1-901983-53-6
• Whitaker, Norman & Hartleb, Glenn (1960), 365 Selected Endings

External links

• Filipowicz - Smederevac (1966) game at Chessville - The Mad Aussie's Chess Trivia

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