Swiss Pairing Rules

(As used by the Khandallah and Upper Hutt Pétanque Clubs)

    Introduction

  1. These rules aim to standardise the pairing procedures in use for Swiss system tournaments. Each pairing will be inevitable, thus allowing a player to predict and confirm the tournament director's selection of his/her opponent with a consequent gain in confidence in the conduct of the event, and in preparation for his/her next game.

  2. There are three basic principles of the Swiss system which must be followed:
    1. No player may be paired with the same opponent twice;
    2. Each player must be paired with an opponent on the same score if at all possible;
    3. Every player who cannot be paired with an opponent on the same score must be paired with an opponent whose score is as close as possible to his/her own.

    Preparation of Cards and Ranking of Players

  3. A pairing card should be prepared for each player and ruled into columns labelled Round Number, Opponent, Result and Running Total.

  4. The pairing cards should be sorted into the order of the players' (or teams') strength. If there is no standardised ranking available then the players shall be ranked by lot.

  5. For a tournament with N players ranking numbers should be indicated on each card ranging from 1 for the strongest player to N for the weakest. Rank number remains unchanged throughout the tournament.

    6. Card Order

  6. Prior to drawing each round the cards must be arranged in the numerical order of the player's progress scores with high scores on top and low scores below. Within each score group the cards are arranged in rank order. For round one, since no player has yet scored, there is only one score group and the whole pack is therefore arranged initially in rank order with 1 on top and N at the bottom.

    7. Byes

  7. If N is odd, before drawing each round a bye is allocated to the lowest scorer or to the lowest ranked among those who share the lowest score. No player may receive a bye twice.

    8. Order of Pairing

  8. Before drawing each round the median score group (i.e. the score group containing the median player) is ascertained. If the median score group falls between two score groups the higher score group is taken. Score groups are first paired from the top down to the median score group, then from the bottom up towards the median score group, and finally the median score group is paired.

    9. Method of Pairing

  9. A pairing is made by first selecting a player and then by selecting an eligible opponent, both selections being inevitable. Pairing is based entirely on the progress scores and on the ranking of the players.

    10. Selecting the Player

  10. When pairing a top or median score group of unpaired contestants the player is always the top ranked contestant in the group. From a bottom score group the player is always the contestant of lowest rank.

    11. Selecting the Opponent

  11. The opponent is that eligible group member whose card lies nearest to being P/2 places (if P is even) or (P+1)/2 places (if P is odd) away from the player's card where P is the number of members in the score group.1

    12. Example: If there are 8 equal scorers to be paired off (represented in their rank order by the numbers 1 to 8) then, the pairings will be 1-5, 2-6, 3-7 and 4-8 assuming that none of these pairs have already met. If there are 9 such players their pairings will be 1-6, 2-7, 3-8 and 4-9. Number 5 will be paired within the neighbouring score group.

    Ineligible Opponents

  12. If a pairing is impossible because the player has already met the opponent then the player is paired against the next eligible opponent in the same half of the group. If this pairing is also impossible the process is continued until an eligible opponent is found.

    13. Example: For a group of 8 equal scorers represented in rank order by the numbers 1 to 8 where #2 has already played #6 and #7 the pairing would be 1-5, 2-8, 3-6 and 4-7.

  13. If it is impossible to find an eligible opponent in the correct half of the group then the previous pairing (if any) made in the same group is cancelled and the player from the cancelled pairing is paired against the next eligible opponent. This process is continued until each player in the top half of the group is paired with an opponent in the bottom half.

    14. Example: For a group of 8 equal scorers represented in rank order by the numbers 1 to 8 where #2 has already played #6, #7 and #8 the pairings would be 1-6, 2-5, 3-7 and 4-8.

  14. If it is not possible to pair each player in the top half of the group with an opponent in the bottom half then pairings may be made within the same half but the principle of pairing the top half against the bottom half in as close as possible to consecutive order must be maintained.

    15. Unequal pairings

  15. If, after the application of rules 10-13, a player cannot be found an opponent in his/her score group then his/her opponent is that eligible contestant in the adjacent unpaired score group whose card lies closest to the player's group. If none in this adjacent group is eligible then the previous pairing is cancelled, the player from that cancelled pairing is paired instead with the next eligible opponent under the pairing rules, and the pairing of the original player is attempted again. This process is continued until each unpaired player is paired with an opponent in the adjacent score group.

  16. If after the application of rule 14, a player cannot be found an opponent in the adjacent score group then the opponent must be found in the next score group and so on following the principles of rule 14.

    17. Pairing Impasse

  17. If at any stage of drawing a round the player cannot be allocated an opponent because s/he has already played all the remaining unpaired contestants then the pairing last made is cancelled, the player from that cancelled pairing is paired instead with the next eligible opponent available under the pairing rules, and the pairing of the original player is attempted again. This procedure may be repeated if necessary and may even be extended to the cancellation also of the immediately preceding pairing if that proves necessary, to ensure that all players are paired with suitable eligible opponents.

    18. Updating the Cards

  18. On completion of the all games in any round the results should be entered on each pair of cards, the players' progress scores should be revised, and the cards should be re-sorted into the order described in rule 5 preparatory to drawing the following round.

    19. Appeals

  19. Any competitor may appeal if these rules are not strictly observed. An appeal can only be made prior to the start of the round for which the irregularity is alleged to have occurred. Such an appeal should be upheld if it is justified and, if it is in regard to an incorrect method of making the draw, another draw should be made.

1 In the Swiss tournament regulations used by the Khandallah Pétanque Club only the direct pairing method is used. Other tournament organisers may use a mix of direct and reverse parings. Under the reverse pairing method the opponent is that eligible group member whose card lies furthest away from the player's card.

Example

For a group of 8 equal scorers represented in rank order by the numbers 1 to 8 the pairings will be 1-8, 2-7, 3-6 and 4-5. For a group of 9 such players their reverse pairings are 1-9, 2-8, 3-7 and 4-6 assuming none of these pairs has already played. Number 5 would be paired within the neighbouring score group. [Return]