Fifty-move rule

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 (fifty moves by each side). The intended reason for the rule is so that a player with no chance to win cannot be obstinate and play on indefinitely (Hooper & Whyld 1992), or seek a win purely due to an opponent's fatigue. All of the basic checkmates can be accomplished in well under fifty moves.

In the 20th century it was discovered that some positions of certain endgames can only be won in more than fifty moves (without a capture or a pawn move). The rule was changed to include certain exceptions in which one hundred moves were allowed with particular material combinations. However, more and more exceptions were discovered and in 1992 FIDE abolished all such exceptions and reinstated the strict fifty-move rule.

Statement of rule

The relevant part of the official FIDE laws of chess is rule 9.3:

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 does not 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 this way; but 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).

Games drawn under the fifty-move rule before the endgame are rare. One example is the game Filipowicz versus Smederevac, Polanica Zdrój 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.

Examples

Timman vs. Lutz

Timman vs. Lutz, 1995
a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h Position after 69. Rxg3, the 50-move count starts here a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h Position before 121... Rb5+?, draw claimed

In this 1995 game between Jan Timman and Christopher Lutz, an endgame with a rook and bishop versus a rook occurred. White is striving for the winning Philidor position while Black is employing the drawing Cochrane Defense and the "second-rank defense" (see rook and bishop versus rook endgame). Black was defending well in the difficult defense and could have claimed a draw on the 119th move. Lutz notes that he claimed a draw on move 121, ironically when making a move that gets into a losing position (Lutz 1999:129–32).

Karpov vs. Kasparov

Karpov vs. Kasparov, 1991
a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h Position after 63. Kxh4, the last capture	a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h Position after 112... Kh8

A draw by the fifty-move rule could have been claimed after Black's 112th move in a 1991 game between Anatoly Karpov and Garry Kasparov, but neither player claimed it. The last capture occurred on White's 63rd move (and the last pawn move occurred before that). By FIDE rule 9.3 part (a), White could have written his 113th move (which wouldn't have been a capture or pawn move) on his scoresheet and claimed a draw. By FIDE rule 9.3 part (b), after White's 113th 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

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

Lputian vs. Haroutjunian

Lputian vs. Haroutjunian, 2001
a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h Position after 86. h6 (the last pawn move of the game)	a b c d e f g h 8 8 7 7 6 6 5 5 4 4 3 3 2 2 1 1 a b c d e f g h Position after 142. Qf6+, Black could claim a draw but resigned

An unusual occurrence happened in a game in the 2001 Armenian Championship between Smbat Lputian (who won the championship) and Gevorg Haroutjunian. The last pawn move was on White's 86th move and no captures occurred after it. (The game was a theoretical draw from before here until Black's 141st move.) Black could have claimed a draw after White's 136th move (or any of the subsequent moves). Instead, the game continued and Black resigned on his 142nd move – even though the right to claim a draw was still in effect (Nunn 2010:303–5).

History

The rule, which was introduced by Ruy López de Segura in his 1561 book, has a long history (Stiller 1996:153). At one time, it was believed that all winnable games could be won without exceeding the fifty-move rule. However, in the early twentieth century, some exceptions were found, including A. A. Troitsky's analysis of the two knights endgame as well as the endgame of a rook and bishop versus a rook. The rules of chess were revised several times to admit exceptions to the fifty-move rule for certain specific situations. Early on, the fifty-move rule applied to tournament games but not to match games (Troitzky 2006:197).

During the time periods when the fifty-move rule admitted exceptions, there were a number of revisions. 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) (Speelman, Tisdall & Wade 1993:382). In 1952 FIDE revised the law, allowing for one hundred move in such positions but requiring that players agree to an extension for these positions before the first move is made. This was still in effect in 1960. The positions were not specified in the rules, to allow for the possibility of more positions requiring more than fifty moves to be discovered (which is what happened). These positions were understood to require more than fifty moves:

1. rook and bishop versus a rook
2. two knights versus a pawn safely blocked by a knight behind Triotsky line
3. rook and pawn on a2 versus a bishop on black squares and a pawn on a3, plus the equivalent positions in the other corners (Whitaker & Hartleb 1960).

Article 12.4 of the 1965 FIDE rules states:

The number of moves can be increased for certain positions, provided that this increase in number and these positions have been clearly established before the commencement of the game.

Harkness notes that "Some of these unusual positions have been established and accepted by FIDE.", including two knights versus a pawn (Harkness 1970:52). The 1975 and 1977 versions of the rules included the same wording (also not specifying the positions or the number of moves) (Morrison 1975:25), (Morrison 1978:21).

In 1984 the rule was modified and it became Article 10.9. Now one hundred moves were explicitly specified and the positions above were listed in the rule (Kazic, Keene & Lim 1985:24–25). (The language about the positions and number of moves having to be specified in advance of the game was dropped.) Ken Thompson's investigations in the 1980s using the Belle chess computer discovered numerous endgames winnable in more than fifty moves. However, these often involved seemingly random moves that defied human comprehension or analysis, in situations that would hardly ever occur in real gameplay. In 1989 the rule (still Article 10.9) was changed to 75 moves, and the listed positions were:

1. rook and bishop versus rook
2. Two knights versus a pawn (no mention of the Troitsky line)
3. A queen and a pawn on the seventh rank versus a queen (see queen and pawn versus queen endgame)
4. Queen versus two knights (see pawnless chess endgame#Queen versus two minor pieces)
5. Queen versus two bishops
6. Two bishops versus a knight (see pawnless chess endgame#Minor pieces only) (FIDE 1989:22-23).

The rule was changed to allow for fifty moves in all positions. Some sources say that the 1989 rule was in effect only a "year or so" or a "few years" (Speelman, Tisdall & Wade 1993:382), (Lutz 1999:130) but one source of the 1992 rules gives the pre-1984 wording: "... increased for certain positions if it was announced in advance" (Goichberg, Jarecki & Riddle 1993:312). By 2001 the rule was Article 9.3 and allowed fifty moves for all positions (Schiller 2003:27–28).

Research in the field of how many moves are required to win certain endgames has continued. Exhaustive retrograde analysis using faster computers to build endgame tablebases has uncovered many more such endgames, often of previously unsuspected length. As of 2008, the record is 517 moves (assuming optimal play by both sides) to make a piece capture or exchange that achieves a simpler and more obviously winnable sub-endgame, for a particular position involving a queen and knight versus a rook, bishop, and knight.

Many of the longest games on record involve the rook and bishop versus rook endgame, when the rule for more moves was in effect. (See pawnless chess endgame and rook and bishop versus rook endgame.)

See also

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

Notes

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

• FIDE (1989), The Official Laws of Chess, Macmillian, ISBN 0-02-028540-X
• Goichberg, Bill; Jarecki, Carol; Riddle, Ira Lee (1993), U.S. Chess Federation's Official Rules of Chess (4th ed.), McKay, ISBN 978-0-8129-2217-2
• Harkness, Kenneth (1970), Official Chess Rulebook, McKay, ISBN 0-679-13028-4
• Hooper, David; Whyld, Kenneth (1992), The Oxford Companion to Chess (2nd ed.), Oxford University Press, ISBN 0-19-866164-9
• Kazic, Bozidar; Keene, Raymond; Lim, Kok Ann (1985), The Official Laws of Chess, Batsford, ISBN 0-7134-4802-4
• Lutz, Christopher (1999), Endgame Secrets: How to plan in the endgame in chess, Batsford, ISBN 978-0-7134-8165-5
• McCrary, John (2004), "The Evolution of Special Draw Rules", Chess Life (November): 26–27
• Morrison, Martin (1975), Official Rules of Chess, McKay, ISBN 0-679-14039-5
• Morrison, Martin (1978), Official Rules of Chess (2nd ed.), McKay, ISBN 0-679-14043-3
• Nunn, John (2010), Nunn's Chess Endings, volume 1, Gambit Publications, ISBN 978-1-906454-21-0
• Speelman, Jon; Tisdall, Jon; Wade, Bob (1993), Batsford Chess Endings, B. T. Batsford, ISBN 0-7134-4420-7
• Schiller, Eric (2003), Official Rules of Chess (2nd ed.), Cardoza, ISBN 978-1-58042-092-1
• Stiller, Lewis (1996), "On Numbers and Endgames: Combinatorial Game Theory in Chess Endgames", in Nowakowski, Richard (ed.), Multilinear Algebra and Chess Endgames, Cambridge University Press, ISBN 0-521-57411-0
• Troitzky, Alexey (2006), Collection of Chess Studies (1937), Ishi Press, ISBN 0-923891-10-2
• Whitaker, Norman; Hartleb, Glenn (1960), 365 Selected Endings

Further reading

• Just, Tim; Burg, Daniel B. (2003), U.S. Chess Federation's Official Rules of Chess (5th ed.), McKay, ISBN 0-8129-3559-4

• Redman, Tim (1987), U.S. Chess Federation's Official Rules of Chess (3rd ed.), McKay, ISBN 0-679-14154-5