Threefold repetition

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This article uses algebraic notation to describe chess moves.

In chess, and in some other abstract strategy games, the threefold repetition rule states that a player can claim a draw if the same position occurs three times, or will occur after their next move, with the same player to move, and with each player having the same set of legal moves each time, including the right to capture en passant and the right to castle. The game is not automatically drawn if this happens: one of the players, on their move, must claim the draw with the arbiter.

1 The rule
2 Examples
3 Interesting situations
4 History
5 See also
6 References
7 External links

[edit] The rule

The relevant rule in the FIDE laws of chess is 9.2, which reads:

The game is drawn, upon a correct claim by the player having the move, when the same position, for at least the third time (not necessarily by sequential repetition of moves)

a. is about to appear, if he first writes his move on his scoresheet and declares to the arbiter his intention to make this move, or

b. has just appeared, and the player claiming the draw has the move.

Positions as in (a) and (b) are considered the same, if the same player has the move, pieces of the same kind and colour occupy the same squares, and the possible moves of all the pieces of both players are the same.

Positions are not the same if a pawn that could have been captured en passant can no longer be captured or if the right to castle has been changed.

While the rule does not require that the position occur thrice on consecutive moves, it happens this way very often in practice, typically with one of the kings being put into perpetual check. The intermediate positions don't matter — they can be the same or different. The rule applies to positions, not moves.

[edit] Examples

Fischer-Petrosian, 1971. Position after 30. Qe2, after 32. Qe2, and after 34. Qe2.

In the third game of the 1971 Candidates Final Match between Bobby Fischer and Tigran Petrosian, Petrosian (with a better position) accidentally allowed a repeated position (see diagram). Play continued:

30... Qe5
31. Qh5 Qf6
32. Qe2 (second time) Re5
33. Qh5 Rd5?
34. Qe2 (third time)

making the third appearance of the position with Black to move and Fischer claimed the draw (Plisetsky & Voronkov 2005:283-84).

Players sometimes repeat a position once not in order to draw, but to gain time on the clock (when an increment is being used) or to bring themselves closer to the time control (at which point they will receive more time). Occasionally, players miscount and inadvertently repeat the position more than once, thus allowing their opponent to claim a draw in an unfavourable position (Adams-Ponomariov, Wijk aan Zee 2005 may have been a recent example of this [1]).

[edit] Interesting situations

Karpov-Miles, Tilburg 1986, position after 22. Nb5, 24. Nb5, and 26. Nb5

The clause about the right to take en passant and the right to castle is a subtle but important one. In a game between grandmasters Anatoly Karpov and Anthony Miles (Tilburg 1986), Karpov had less than five minutes remaining on his clock, in which to finish a specified number of moves or forfeit the game. He claimed a draw by repetition after checking his scoresheet carefully, whereupon it was pointed out to him that in the first occurrence of position, Black's king had had the right to castle, whereas in the second and third it had not. Tournament rules stipulated that a player be penalized with three minutes of their time for incorrect claims, which left Karpov's flag on the verge of falling! By then, Miles had had his fun, and took the draw. See the diagram for the position after 22. Nb5. The game continued 22. ... Ra4 23. Nc3 Ra8 24. Nb5 Ra4 25. Nc3 Ra8 26. Nb5. Black could castle queenside in the diagram, but not when the position was repeated.

Fischer-Spassky, 1972, game 20, final position

In the twentieth game of the 1972 Bobby Fischer-Boris Spassky match (the Match of the Century), Fischer claimed a draw because of threefold repetition. Spassky did not dispute it and the arbiter agreed. After the draw had been agreed, it was pointed out that the position had occurred after White's forty-eighth and fiftieth moves, and again after Black's fifty-fourth move (the final position). So the claim was actually invalid because it was not the same player's turn to move in all three instances (Alexander 1972:137-38).

[edit] History

Pest-Paris, Position after 19. Nc5. It reoccurred after White's twenty-first and twenty-third move.

At various times in the history of chess, the rule has been variously formulated. In Tim Harding's MegaCorr database (a collection of correspondence chess games), the notes to a game between the cities of Pest and Paris played between 1842 and 1845 state that a sixfold repetition was necessary to claim a draw. The game went: 1.e4 e5 2.Nf3 Nf6 3.Nxe5 d6 4.Nf3 Nxe4 5.d4 d5 6.Bd3 Bd6 7.O-O O-O 8.c4 Be6 9.Qc2 f5 10.Qb3 dxc4 11.Qxb7 c6 12.Bxe4 fxe4 13.Ng5 Bf5 14.Nc3 Qd7 15.Qxd7 Nxd7 16.Ngxe4 Bc7 17.Re1 Rab8 18.Re2 Nb6 19.Nc5 Bd6 20.N5e4 Bc7 21.Nc5 Bd6 22.N5e4 Bc7 23.Nc5 Bd6 24.N5e4 Bc7 25.Nc5 Bd6 26.N5e4 Bc7 27.Nc5 and now instead of taking the sixfold repetition draw with 27...Bd6 28.N5e4 Bc7, Paris diverged with 27...Bd3 and went on to lose the game.