In a Swiss system tournament, nothing causes a player revolt faster than hearing: "Wait, I already played this person in Round 2!" or "Why have I had Black three times in a row?"
Under official FIDE rules, avoiding rematches is an absolute requirement, and balancing pieces (White and Black) is a primary objective. Here is how tournament engines prevent pairing conflicts.
1. The Absolute Rules of Swiss Pairings
- Zero Rematches: Two players shall not be paired against each other more than once in the same tournament.
- No Double Bye: A player who has already received an unplayed full-point pairing bye cannot receive another bye.
- Color Balance Limit: The difference between the number of White games and Black games for any player must not exceed 2, and after the final round, must not exceed 1 (or 0 if an even number of games were played).
- No Three Consecutive Same Colors: No player shall be given the same color three times in a row, except in extraordinary circumstances in the final round to avoid an unpairable bracket.
2. What are "Floaters"?
When an odd number of players share a score group (e.g. 5 players have 3.0/4), one player must be paired against someone from a different score bracket. This player is called a Downfloater (or an Upfloater from the perspective of the lower group).
Frequently Asked Questions
Under official FIDE Swiss rules, no. An arbiter or pairing engine must never pair two players together if they have already played each other in a previous round of the same tournament.
As an absolute rule, no player may be assigned the same color three times in succession. An exception is only permissible in the very final round if an absolute pairing deadlock occurs.
A floater is a player who must be paired against an opponent in a different point bracket because their own score group contains an odd number of eligible players.
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