DOUBLE-SWISS SYSTEM

Approved by the Council on 28/10/2025

Applied from 1st February, 2026

0.      Preface

Double-Swiss competitions are tournaments in which every pairing is a match between two players. The match consists of two games played in succession, with alternating colours and with points assigned for each game.

In a Double-Swiss competition, the usual results of a match are 2-0, 1½-½, 1-1, ½-1½, or 0-2. Also, since a game can (rarely) end ½-0, 0-½, or 0-0, other possible match results are 1½-0, 1-½, ½-1, 0-1½, 1-0, ½-½, 0-1, ½-0, 0-½, and 0-0.

A match ends by forfeit only if at least one player forfeits both games. In this case, the same pairing may be repeated in a later round. In all other cases, the match is considered as regularly played and, for the purposes of tie-breaks and standings, any forfeited (single) game shall be treated as played. (This rule does not apply to rating.)

Byes (requested or assigned) apply only to matches, never to individual games.

1.      Introductory Remarks and Definitions

1.1     Tournament Pairing Number ("TPN")

For the definition and management of TPNs, see Article 2 of the General Handling Rules for Swiss Tournaments (Initial Order and Late Entries).

1.2     Order

For pairings purposes only, the players are ranked in order of, respectively

1.2.1      Score

1.2.2      TPN (in ascending order)

1.3     Scoregroups and Pairing Brackets

1.3.1      A scoregroup is composed of all the players with the same score.

1.3.2      A (pairing) bracket is an even numbered group of players all to be paired. It is composed of players coming from the same scoregroup (called resident players) and (possibly) of players coming from lower scoregroups (called upfloaters).

1.4     Pairing-Allocated-Bye (PAB)

Should the number of players to be paired be odd, one player is not paired. This player receives a pairing-allocated bye: no opponent, no colour, and as many points as if the player had played a match winning a game and drawing the other, unless the rules of the tournament state otherwise. This number of points shall be the same for all pairing-allocated byes (See Article 3 of the Basic Rules for Swiss Systems).

1.5     Floaters

A floater is a player who plays against an opponent with a different score.

1.6     Colours

A player is said to have (had) a colour (White or Black) in a match if at least one game of the match was actually played and the player was scheduled to play the first game with that colour.

2.      Pairing Criteria

2.1     Absolute Criteria

No pairing shall violate the following absolute criteria:

2.1.1      [C1] See the Basic Rules for Swiss, Article 2 (Two participants shall not play against each other more than once).

2.1.2      [C2] A player who has already received a pairing-allocated bye or won a match by forfeit (or been given a FIDE-deprecated full-point bye) shall not receive the pairing-allocated bye.

2.2     Completion Criterion

2.2.1      [C3] A pairing complying with all the absolute criteria (see Article 2.1) shall always exist for all players not yet paired.

2.3     Quality Criteria

In order to best pair all players of the top-scoregroup (see Article 3.2), comply as much as possible with the following criteria, given in descending priority:

2.3.1      [C4] Minimise the number of upfloaters.

2.3.2      [C5] Minimise the score differences (taken in descending order) in the pairs involving upfloaters, i.e. maximise the scores (taken in ascending order)  of the upfloaters.

2.3.3      [C6] Unless all the players in the following scoregroup became or are upfloaters (thus this scoregroup is now empty), choose the set of upfloaters so that criteria [C1], [C3] and [C4] (see Articles 2.1.1, 2.2.1 and 2.3.1) are complied with in the bracket where this (not empty) scoregroup is paired.

Note:   Only the mentioned scoregroup is involved, even though some of the upfloaters come from lower scoregroups.

2.3.4      [C7] With the exception of the last round, minimise the number of upfloaters who were floaters in the previous round (see Article 1.5).

2.3.5      [C8] With the exception of the last round, minimise the number of upfloaters' opponents who were floaters in the previous round (see Article 1.5).

3.      Pairing Definitions and Rules

3.1     Legal Pairing

3.1.1      A pairing is legal when the absolute criteria [C1] and [C2] (see Article 2.1) are complied with.

3.1.2      During the pairing, the completion criterion [C.3] (see Article 2.2) is also to be complied with.

3.2     Top-Scoregroup

During the pairing, it is the group of one or more players who have the highest score among the players who are yet to be paired.

3.3     Round-Pairing Outlook

3.3.1      The pairing of a round (called round-pairing) is complete if all the players (except at most one, who receives the pairing-allocated bye) have been paired and the absolute criteria [C1] and [C2] (see Article 2.1) have been complied with.

3.3.2      The pairing process consists of the following steps:

1. The first step in the pairing process is the assignment of the pairing-allocated-bye (if needed) by applying Article 3.4.
2. Then, the top-scoregroup is combined, when needed, with a set of upfloaters (selected according to Article 3.5), to form a bracket that is paired according to Article 3.6.
3. The previous step-2 is then repeated until the round-pairing is complete.
4. Colours are then assigned according to Article 4.

3.3.3      If it is impossible to complete a round-pairing, the Chief Arbiter shall decide what to do.

3.4     Pairing-Allocated-Bye Assignment

The pairing-allocated-bye is assigned to the player who:

3.4.1      leaves a legal pairing for all players

3.4.2      has the lowest score

3.4.3      has played the highest number of matches

3.4.4      has the largest TPN

3.5     Selection of Upfloaters for the Top-Scoregroup

3.5.1      All players with a lower score than the resident players of the top-scoregroup are potential upfloaters.

3.5.2      Consider all sets of potential upfloaters that comply with [C4] and [C5] (see Articles 2.3.1 and 2.3.2).

Note:   This somehow determines the number of upfloaters in the set and their scores.

3.5.3      In each set, the potential upfloaters, identified by their TPN, are first sorted by descending score and then, when scores are equal, by ascending TPN.

3.5.4      These sets are then sorted among themselves by the lexicographic order of their TPNs.

Example:   Let's assume that 2,6,8 have 3 points, and 1,3,5 have 2.5 points. [C4] determines that a set of three upfloaters is needed, and [C5] determines that two upfloaters must have 3 points and the other 2.5 points. The possible set of upfloaters are: {2,6,1} < {2,6,3} < {2,6,5} < {2,8,1} < {2,8,3} < {2,8,5} < {6,8,1} < {6,8,3} < {6,8,5}, already sorted in the proper order.

3.5.5      Choose the first set that, together with the top-scoregroup, produces a legal pairing that also complies with criteria [C6] and [C7] (see Articles 2.3.3 and 2.3.4) - besides [C4] and [C5] (see Articles 2.3.1 and 2.3.2), which it complies with by construction.

3.6     Pairing of a Bracket

3.6.1      A pairing is a sequence of pairs that includes all players in the bracket. For each pair, the player with the smaller TPN is the top member of the pair; the player with the larger TPN is the bottom member of the pair.

3.6.2      A pairing is identified by the TPNs of the top members of each pair sorted in ascending order, followed by the TPNs of the bottom member of the corresponding pair.

Example:   If  11-24  16-6  10-9  8-4 is a pairing, its identifier is 4 6 9 11 8 16 10 24.

3.6.3      Pairings are sorted by the lexicographic order of their identifiers.

3.6.4      Choose the first pairing that also complies with criteria [C1] and [C8] (see Articles 2.1.1 and 2.3.5 - besides the other criteria, which it complies with by construction).

4.      Colour Allocation Rules

4.1     The initial-colour is the colour determined by drawing of lots before the pairing of the first round.

4.2     In a pair, the higher-ranked-player ("HRP") is the player with the higher score or, if both players have the same score, the smaller TPN.

4.3     For each pair apply (with descending priority):

4.3.1      When both players have yet to play a match, if the HRP has an odd TPN, give the HRP the initial-colour; otherwise, give the HRP the opposite colour.

4.3.2      Give White to the player with the lower number of Whites.

4.3.3      Alternate the colours to the most recent time in which one player had White and the other Black.

Note:     Always consider Article 3.4 of the General Handling Rules for Swiss Tournaments.

4.3.4      Alternate the colour of the HRP from the HRP's last played round.

4.3.5      Alternate the colour of the HRP's opponent from the HRP's opponent last played round.

4.4     The player who gets White plays the first game of the match with White and the second with Black (see also the Preface and Article 1.6).