Swiss system tournament
Encyclopedia
A Swiss-system tournament is a commonly used type of tournament
where players or teams need to be paired to face each other for several rounds of competition. This type of tournament was first used in a Zurich
chess tournament in 1895, hence the name "Swiss system". The Swiss system is used when there are too many players to play a round-robin tournament
. It is also preferable to an elimination tournament
if all of the players can play at the same time (e.g. as in chess
but not in tennis
, due to a limited number of tennis court
s).
For the rest of the article, the term player will be used to refer to the parties involved. A team may be considered as a player when teams are playing against other teams.
A Swiss tournament goes for a predetermined number of rounds, with all of the players taking part in each round. In each round two players compete head-to-head. All players participate in the entire tournament – none are eliminated. The winner (and top places) of the tournament is based on the final scores of the players. The final score is based on the number of points they accumulated for each round. In some competitions, one point is awarded to the winner of a round; in others, a number of points can be earned each round.
The principle of a Swiss tournament is that each player will be pitted against another player who has done as well (or poorly) as him or herself. For the first round, players are paired either according to some pattern or randomly (according to common practice in that type of game or sport). For subsequent rounds, players are sorted according to their cumulative scores and players are assigned opponents that have the same or similar score to that point. One proviso is that the same players never oppose each other twice. There may be adjustments made to the natural order. For instance, in chess
the pairings may be changed to equalize the number of times a player has been White
and Black.
The Swiss system is commonly used in chess
, Go, bridge
, Scrabble
, squash
, Quiz Bowl, Magic: The Gathering
, Eight Ball
, Reversi
and other games .
or last year's performance. Players who win receive a point, those who draw
receive half a point and players that lose receive no points. Win, lose, or draw, all players proceed to the next round where winners are pitted against winners, losers are pitted against losers, and so on. In subsequent rounds, players face opponents with the same (or almost the same) score. No player is paired up against the same opponent twice, however. In chess
it is also attempted to ensure that each player plays an equal number of games with white and black, alternate colors in each round being the most preferable, and a concerted effort is made not to assign the same color three times in a row.
The basic rule is that players with the same score are ranked according to rating. Then the top half is paired with the bottom half. For instance, if there are eight players in a score group, number 1 is paired with number 5, number 2 is paired with number 6 and so on. Modifications are then made to balance colors and prevent players from meeting each other twice.
The detailed rules of how to do the pairing are usually quite complicated and often the tournament organizer has access to a computer to do the pairing. If the rules are strictly adhered to, the organizer has no discretion in pairing the round. See the link below for detailed pairing rules from FIDE.
.
, that is the binary logarithm
of the number of players rounded up. Therefore three rounds can handle eight players, four rounds can handle sixteen players and so on. If fewer than this minimum number of rounds are played, it can happen that two or more players finish the tournament with a perfect score, having won all their games but never faced each other.
Compared to a knockout tournament the Swiss system has the inherent advantage of not eliminating anyone. That means that a player can enter such a tournament knowing that he will be able to play in all rounds, regardless of how well he does. The worst that can happen in this respect is being the player left over when there is an odd number of players. The player left over receives a bye
, meaning the player does not play that particular round but receives a point. The player is reintroduced in the next round and will not receive another bye.
Another advantage compared to knockout tournaments is that the final ranking gives some indication of relative strength for all contestants, not just for the winner of the tournament. As an example, the losing finalist in a knockout tournament may not be the second best contestant; that might have been any of the contestants eliminated by the eventual tournament winner in earlier rounds.
A Swiss system tournament does not always end with the exciting climax
of the knockout's final however. Sometimes a player may have picked up such a great lead that by the last round he is assured of winning the tournament even if he loses the last game. One fairly common fix for this dilemma
is to hold single elimination rounds among the top scorers. In Scrabble tournaments a player with such a strong lead will often be paired against the highest-placed player who cannot possibly finish in the prize-winning zone; this process is known as Gibsonization (also known as the Gibson Rule) after it was first applied to the U.S. Scrabble Champion David Gibson
in the 1995 All-Stars tournament. He is the all-time top money winner in the history of Scrabble, and earned a particular reputation by clinching victory in major events before the final round. Because of this, players are said to be Gibsonized: after winning, they are paired with lower-ranked players to avoid affecting the ranking of runners-up.
An additional disadvantage is that, while the players finishing near the top are typically those with the best performances, and those finishing near the bottom are those with the worst performances, the players in the middle tend to be jumbled with little meaningful order. For example, at a recent edition of the European Chess Championship, players scoring 5½/11 had performance ratings ranging from to 2189 to 2559; such a difference suggests that the stronger-performing player would score more than 90% against the weaker-performing one. One player with a 2441 performance rating scored two and a half points better than one performing at 2518.
The system has been used for pool trialing particularly in England. The way to overcome there being multiple players with the same perfect score is to eliminate players after a certain amount of losses. So if you lose three you are out. This will then leave a final match where only one person will end with a perfect score and automatically qualify. This will then leave the right amount of people to play a round robin even so to find the final amount of entrants.
Compared with a round-robin tournament
, a Swiss can handle many players without requiring an impractical number of rounds. An elimination tournament
is better suited to a situation in which only a limited number of games may be played at once, e.g. tennis
. In a Swiss system, all players can be playing a round at the same time.
For the first two rounds, players who started in the top half have one point added to their score for pairing purposes only. Then the first two rounds are paired normally, taking this added score into account. In effect, in the first round the top quarter plays the second quarter and the third quarter plays the fourth quarter. Most of the players in the first and third quarters should win the first round. Assuming this is approximately the case, in effect for the second round the top eighth plays the second eighth, the second quarter plays the third quarter and the seventh eighth plays the bottom eighth. That is, in the second round, winners in the top half play each other, losers in the bottom half play each other, and losers in the top half play winners in the bottom half (for the most part). After two rounds, about ⅛ of the players will have a perfect score, instead of ¼. After the second round, the standard pairing method is used (without the added point for the players who started in the top half).
As a comparison between the standard Swiss system and the accelerated pairings, consider a tournament with eight players, ranked #1 through #8. Assume that the higher-ranked player always wins.
Standard Swiss system
Round 1:
#1 plays #5, #1 wins
#2 plays #6, #2 wins
#3 plays #7, #3 wins
#4 plays #8, #4 wins
Round 2:
#1 plays #3, #1 wins
#2 plays #4, #2 wins
#5 plays #7, #5 wins
#6 plays #8, #6 wins
After two rounds, the standings are:
1: 2-0
2: 2-0
3: 1-1
4: 1-1
5: 1-1
6: 1-1
7: 0-2
8: 0-2
Accelerated pairings
Round 1:
#1 plays #3, #1 wins
#2 plays #4, #2 wins
#5 plays #7, #5 wins
#6 plays #8, #6 wins
Round 2:
#1 plays #2, #1 wins
#3 plays #5, #3 wins
#4 plays #6, #4 wins
#7 plays #8, #7 wins
After two rounds, the standings are:
1: 2-0
2: 1-1
3: 1-1
4: 1-1
5: 1-1
6: 1-1
7: 1-1
8: 0-2
Bridge team tournaments, if not played as "Round Robin", usually start with the Swiss system to make sure that the same teams would not play against each others frequently, but in the last one or two rounds there is a switch to the Danish system, especially to allow the first two ranked teams to battle against each others for the victory, even if they have met before during the tournament.
they need to play more rounds to accumulate points. The tournament therefore includes players who want to go for a prize and play several rounds as well as players who only want to play an off game. This system is used by a few chess club
s in Norway
.
is the established way in which Europe
an Go tournaments are run. This differs mainly in that players start at different levels; so the Swiss system is the special case where all players start at the same level. It is named for Lee E. McMahon
(1931–1989) of Bell Labs
.
is the Monrad system. This is very similar to the Swiss System, but deemphasizes ratings, and bases the pairings on the starting number each contestant has received at random before the tournament.
The Danish version is a fairly simple method, players are initially ranked at random, and pairings are modified mainly to avoid players meeting each other twice. The Norwegian system has an optional seeding system for the first round pairings, and within a score group, the pairing algorithm endeavours to give players alternating colors.
depend on the Swiss ladder system to ensure its players get as many challenging matches as possible over the course of the badminton
tournament. The tournaments are meant to promote both the sport and the social aspect of the game, hence its results are not connected to external rankings. Beforehand, players can enroll in three or four categories designed to separate national, regional and recreational players. Players of different clubs are coupled to form doubles and mix doubles. The starting positions on each ladder (singles, doubles and mix doubles) are random. Unlike in official matches a 1-1 draw is possible and games are usually not extended after 21 is reached in order to maximise the number of played matches.
tournament events. They involve teams of four, five, or six players (usually four). In each round, one team plays against another team for several hands, with the north/south pair of the team playing against the east/west pair of the other team. The same hands are played at both tables and each hand is scored by International Match Points (IMPs). The difference in the total IMPs is converted to victory points, with either twenty or thirty victory points split between the two teams, depending on the difference of the IMPs. In the first round, teams are paired essentially randomly. In subsequent rounds, the teams are ranked in order of the number of victory points they have accumulated and the top team plays the second team, the third team plays the fourth team, etc., subject to the proviso that teams do not play each other twice. In the last one ore two rounds there may be a switch to the Danish system to make sure that each team plays the final match according to its actual ranking, even if this results in some teams playing against an opponent they have met already before.
debate competitions have four rather than two teams in each debate. The preliminary round for many such competitions, including the World Universities Debating Championship
, ranks teams by a modified form of Swiss tournament, usually called a tab. "Tab" also denotes to the software used for scheduling of rounds and tabulation of results. Teams are ranked from first to fourth in each debate and awarded from three down to zero points. Teams with similar points totals are grouped off for each successive round. Just as chess Swiss tournaments are arranged to ensure players have a balance of playing with black pieces and white pieces, so too debate tournaments attempt to provide teams with a balance of places in the speaking order (i.e. Opening Government, Opening Opposition, Closing Government, and Closing Opposition). With four competitors rather than two, significantly greater compromise is required to balance the ideal requirements of, on the one hand, a team not meeting the same opponent twice and, on the other hand, a team having a balanced mix of places in the running order.
, uses a Swiss system for most tournaments. Unlike with other Swiss implementations, players receive three points for a win
and only one for a draw. After sufficient rounds to produce one undefeated player, typically the top eight players advance to a single-elimination
stage, with several statistics used as tie-breakers.
tournaments, a system known variously as "modified Swiss", "Portland Swiss", "Fontes Swiss" or "speed pairing" is used, whereby first players are placed in groups of four, and play three rounds of round-robin play, and subsequently are paired as in Swiss pairing, but using the standings as of the second to last round, rather than the last round. This has the advantage of allowing the tournament directors to already know who plays whom by the time given players are finished with a round, rather than making the players wait until all players have finished playing a given round before being able to start the time-consuming pairing process.
Commonly used in Australia, and now in many other countries, is a system known as "Australian Draw". Whereby each round is paired using a normal #1 plays #2, #3 plays #4, etc. except that repeat pairings within a selected range of previous games is forbidden. Often, for shorter tournaments the selected range will be since the very first round of the tournament, thus never having a repeat pairing for the entire tournament. For longer tournaments it is also common to have the first N rounds use the Australian Draw system, and followed by one or more "King Of the Hill" rounds. "King Of the Hill" is a strict #1 plays #2, #3 plays #4, etc. with no regard to previous pairings, thus unlimited repeat pairings are allowed.
Another Scrabble
system based on Swiss pairing is known as "Chew pairing", and has been used at recent North American National and Canadian National Scrabble championships, and since 2005 at the World Scrabble Championship
. Simulations are performed to determine which players are still in contention for each prize and those players are paired so as to balance the right of a low-ranked player to avoid elimination by challenging a high-ranked player with the right of high-ranked players to compete directly with each other for prizes.
In ultimate frisbee it works like this: for each round, the teams earn victory points based on the score difference of their win (or loss). In this way, also a team clearly losing a game is encouraged to fight for every point in order to get more victory points. After each round, teams are ranked according to their victory points. Ties are broken by considering the sum of the current victory points of their opponents. In the next round, neighboring teams in the ranking play each other. In case they have played each other in a previous round, adjustments to the rankings are made. After five rounds of Swiss draw, three playoff rounds (in groups of 8) are played to determine the final placement of the teams. See Swiss Draw in Ultimate Frisbee for more details.
Other tournament systems:
Tournament
A tournament is a competition involving a relatively large number of competitors, all participating in a sport or game. More specifically, the term may be used in either of two overlapping senses:...
where players or teams need to be paired to face each other for several rounds of competition. This type of tournament was first used in a Zurich
Zürich
Zurich is the largest city in Switzerland and the capital of the canton of Zurich. It is located in central Switzerland at the northwestern tip of Lake Zurich...
chess tournament in 1895, hence the name "Swiss system". The Swiss system is used when there are too many players to play a round-robin tournament
Round-robin tournament
A round-robin tournament is a competition "in which each contestant meets all other contestants in turn".-Terminology:...
. It is also preferable to an elimination tournament
Single-elimination tournament
A single-elimination tournament, also called a knockout, cup or sudden death tournament, is a type of elimination tournament where the loser of each match or bracket is immediately eliminated from winning the championship or first prize in the event...
if all of the players can play at the same time (e.g. as in chess
Chess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
but not in tennis
Tennis
Tennis is a sport usually played between two players or between two teams of two players each . Each player uses a racket that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court. Tennis is an Olympic sport and is played at all levels of society at all...
, due to a limited number of tennis court
Tennis court
A tennis court is where the game of tennis is played. It is a firm rectangular surface with a low net stretched across the center. The same surface can be used to play both doubles and singles.-Dimensions:...
s).
For the rest of the article, the term player will be used to refer to the parties involved. A team may be considered as a player when teams are playing against other teams.
A Swiss tournament goes for a predetermined number of rounds, with all of the players taking part in each round. In each round two players compete head-to-head. All players participate in the entire tournament – none are eliminated. The winner (and top places) of the tournament is based on the final scores of the players. The final score is based on the number of points they accumulated for each round. In some competitions, one point is awarded to the winner of a round; in others, a number of points can be earned each round.
The principle of a Swiss tournament is that each player will be pitted against another player who has done as well (or poorly) as him or herself. For the first round, players are paired either according to some pattern or randomly (according to common practice in that type of game or sport). For subsequent rounds, players are sorted according to their cumulative scores and players are assigned opponents that have the same or similar score to that point. One proviso is that the same players never oppose each other twice. There may be adjustments made to the natural order. For instance, in chess
Chess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
the pairings may be changed to equalize the number of times a player has been White
White and Black in chess
In chess, the player who moves first is referred to as "White" and the player who moves second is referred to as "Black". Similarly, the pieces that each conducts are called, respectively, "the white pieces" and "the black pieces". The pieces are often not literally white and black, but some...
and Black.
The Swiss system is commonly used in chess
Chess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
, Go, bridge
Duplicate bridge
Duplicate bridge is the most widely used variation of contract bridge in club and tournament play. It is called duplicate because the same bridge deal is played at each table and scoring is based on relative performance...
, Scrabble
Scrabble
Scrabble is a word game in which two to four players score points by forming words from individual lettered tiles on a game board marked with a 15-by-15 grid. The words are formed across and down in crossword fashion and must appear in a standard dictionary. Official reference works provide a list...
, squash
Squash (sport)
Squash is a high-speed racquet sport played by two players in a four-walled court with a small, hollow rubber ball...
, Quiz Bowl, Magic: The Gathering
Magic: The Gathering
Magic: The Gathering , also known as Magic, is the first collectible trading card game created by mathematics professor Richard Garfield and introduced in 1993 by Wizards of the Coast. Magic continues to thrive, with approximately twelve million players as of 2011...
, Eight Ball
Eight ball
Eight-ball is a pool game popular in much of the world, and the subject of international professional and amateur competition...
, Reversi
Reversi
Reversi is a board game involving abstract strategy and played by two players on a board with 8 rows and 8 columns and a set of distinct pieces for each side. Pieces typically are disks with a light and a dark face, each face belonging to one player...
and other games .
Pairing procedure
The first round is either drawn at random or seeded according to some prior order, such as ratingElo rating system
The Elo rating system is a method for calculating the relative skill levels of players in two-player games such as chess. It is named after its creator Arpad Elo, a Hungarian-born American physics professor....
or last year's performance. Players who win receive a point, those who draw
Tie (draw)
To tie or draw is to finish a competition with identical or inconclusive results. The word "tie" is usually used in North America for sports such as American football. "Draw" is usually used in the United Kingdom, Ireland and the Commonwealth of Nations and it is usually used for sports such as...
receive half a point and players that lose receive no points. Win, lose, or draw, all players proceed to the next round where winners are pitted against winners, losers are pitted against losers, and so on. In subsequent rounds, players face opponents with the same (or almost the same) score. No player is paired up against the same opponent twice, however. In chess
Chess
Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...
it is also attempted to ensure that each player plays an equal number of games with white and black, alternate colors in each round being the most preferable, and a concerted effort is made not to assign the same color three times in a row.
The basic rule is that players with the same score are ranked according to rating. Then the top half is paired with the bottom half. For instance, if there are eight players in a score group, number 1 is paired with number 5, number 2 is paired with number 6 and so on. Modifications are then made to balance colors and prevent players from meeting each other twice.
The detailed rules of how to do the pairing are usually quite complicated and often the tournament organizer has access to a computer to do the pairing. If the rules are strictly adhered to, the organizer has no discretion in pairing the round. See the link below for detailed pairing rules from FIDE.
Final scores and tie-breaking
The tournament lasts for a number of rounds announced before the tournament. After the last round, players are ranked by their score. If this is tied then a tie break score, such as the sum of all their opponents' scores (Buchholz chess rating), can be used: see Tie-breaking in Swiss system tournamentsTie-breaking in Swiss system tournaments
Tie-break systems are used in chess Swiss system tournaments to break ties between players who have the same total number of points after the last round. If the players are still tied after one tie-break system is used, another system is used, and so on, until the tie is broken...
.
Folklore
While the common term 'Swiss pair' has no relation to Pears, a tradition has developed in some quizzes and quiz leagues in the North West of England, whereby a Swiss Pear is presented to the winner of a 'Swiss Pair' tournament or section of a tournament.Analysis, advantages, and disadvantages
Determining a clear winner (and, incidentally, a clear loser) usually requires the same number of rounds as a knockout tournamentSingle-elimination tournament
A single-elimination tournament, also called a knockout, cup or sudden death tournament, is a type of elimination tournament where the loser of each match or bracket is immediately eliminated from winning the championship or first prize in the event...
, that is the binary logarithm
Binary logarithm
In mathematics, the binary logarithm is the logarithm to the base 2. It is the inverse function of n ↦ 2n. The binary logarithm of n is the power to which the number 2 must be raised to obtain the value n. This makes the binary logarithm useful for anything involving powers of 2,...
of the number of players rounded up. Therefore three rounds can handle eight players, four rounds can handle sixteen players and so on. If fewer than this minimum number of rounds are played, it can happen that two or more players finish the tournament with a perfect score, having won all their games but never faced each other.
Compared to a knockout tournament the Swiss system has the inherent advantage of not eliminating anyone. That means that a player can enter such a tournament knowing that he will be able to play in all rounds, regardless of how well he does. The worst that can happen in this respect is being the player left over when there is an odd number of players. The player left over receives a bye
Bye (sports)
A bye, in sports and other competitive activities, most commonly refers to the practice of allowing a player or team to advance to the next round of a playoff tournament without playing...
, meaning the player does not play that particular round but receives a point. The player is reintroduced in the next round and will not receive another bye.
Another advantage compared to knockout tournaments is that the final ranking gives some indication of relative strength for all contestants, not just for the winner of the tournament. As an example, the losing finalist in a knockout tournament may not be the second best contestant; that might have been any of the contestants eliminated by the eventual tournament winner in earlier rounds.
A Swiss system tournament does not always end with the exciting climax
Climax (narrative)
The Climax is the point in the story where the main character's point of view changes, or the most exciting/action filled part of the story. It also known has the main turning point in the story...
of the knockout's final however. Sometimes a player may have picked up such a great lead that by the last round he is assured of winning the tournament even if he loses the last game. One fairly common fix for this dilemma
Dilemma
A dilemma |proposition]]") is a problem offering two possibilities, neither of which is practically acceptable. One in this position has been traditionally described as "being on the horns of a dilemma", neither horn being comfortable...
is to hold single elimination rounds among the top scorers. In Scrabble tournaments a player with such a strong lead will often be paired against the highest-placed player who cannot possibly finish in the prize-winning zone; this process is known as Gibsonization (also known as the Gibson Rule) after it was first applied to the U.S. Scrabble Champion David Gibson
David Gibson (Scrabble)
David Gibson is a mathematics instructor and professional Scrabble player from South Carolina. He was the winner of the 1995 National Scrabble Championship, the 1994 Scrabble Superstars Showdown, and the 2003 Scrabble All Stars Championship...
in the 1995 All-Stars tournament. He is the all-time top money winner in the history of Scrabble, and earned a particular reputation by clinching victory in major events before the final round. Because of this, players are said to be Gibsonized: after winning, they are paired with lower-ranked players to avoid affecting the ranking of runners-up.
An additional disadvantage is that, while the players finishing near the top are typically those with the best performances, and those finishing near the bottom are those with the worst performances, the players in the middle tend to be jumbled with little meaningful order. For example, at a recent edition of the European Chess Championship, players scoring 5½/11 had performance ratings ranging from to 2189 to 2559; such a difference suggests that the stronger-performing player would score more than 90% against the weaker-performing one. One player with a 2441 performance rating scored two and a half points better than one performing at 2518.
The system has been used for pool trialing particularly in England. The way to overcome there being multiple players with the same perfect score is to eliminate players after a certain amount of losses. So if you lose three you are out. This will then leave a final match where only one person will end with a perfect score and automatically qualify. This will then leave the right amount of people to play a round robin even so to find the final amount of entrants.
Compared with a round-robin tournament
Round-robin tournament
A round-robin tournament is a competition "in which each contestant meets all other contestants in turn".-Terminology:...
, a Swiss can handle many players without requiring an impractical number of rounds. An elimination tournament
Single-elimination tournament
A single-elimination tournament, also called a knockout, cup or sudden death tournament, is a type of elimination tournament where the loser of each match or bracket is immediately eliminated from winning the championship or first prize in the event...
is better suited to a situation in which only a limited number of games may be played at once, e.g. tennis
Tennis
Tennis is a sport usually played between two players or between two teams of two players each . Each player uses a racket that is strung to strike a hollow rubber ball covered with felt over a net into the opponent's court. Tennis is an Olympic sport and is played at all levels of society at all...
. In a Swiss system, all players can be playing a round at the same time.
Accelerated pairings
The method of accelerated pairings also known as accelerated Swiss is used in some large tournaments with more than the optimal number of players for the number of rounds. This method pairs top players more quickly than the standard method in the opening rounds and has the effect of reducing the number of players with perfect scores more rapidly (by approximately a factor of 2 after two rounds).For the first two rounds, players who started in the top half have one point added to their score for pairing purposes only. Then the first two rounds are paired normally, taking this added score into account. In effect, in the first round the top quarter plays the second quarter and the third quarter plays the fourth quarter. Most of the players in the first and third quarters should win the first round. Assuming this is approximately the case, in effect for the second round the top eighth plays the second eighth, the second quarter plays the third quarter and the seventh eighth plays the bottom eighth. That is, in the second round, winners in the top half play each other, losers in the bottom half play each other, and losers in the top half play winners in the bottom half (for the most part). After two rounds, about ⅛ of the players will have a perfect score, instead of ¼. After the second round, the standard pairing method is used (without the added point for the players who started in the top half).
As a comparison between the standard Swiss system and the accelerated pairings, consider a tournament with eight players, ranked #1 through #8. Assume that the higher-ranked player always wins.
Standard Swiss system
Round 1:
#1 plays #5, #1 wins
#2 plays #6, #2 wins
#3 plays #7, #3 wins
#4 plays #8, #4 wins
Round 2:
#1 plays #3, #1 wins
#2 plays #4, #2 wins
#5 plays #7, #5 wins
#6 plays #8, #6 wins
After two rounds, the standings are:
1: 2-0
2: 2-0
3: 1-1
4: 1-1
5: 1-1
6: 1-1
7: 0-2
8: 0-2
Accelerated pairings
Round 1:
#1 plays #3, #1 wins
#2 plays #4, #2 wins
#5 plays #7, #5 wins
#6 plays #8, #6 wins
Round 2:
#1 plays #2, #1 wins
#3 plays #5, #3 wins
#4 plays #6, #4 wins
#7 plays #8, #7 wins
After two rounds, the standings are:
1: 2-0
2: 1-1
3: 1-1
4: 1-1
5: 1-1
6: 1-1
7: 1-1
8: 0-2
Danish system
The Danish system works in principle like the Swiss system, only without the restriction that no players can meet for a second time, so it's always #1 vs. #2, #3 vs. #4 etc.; somewhere also referred to as "Luton system".Bridge team tournaments, if not played as "Round Robin", usually start with the Swiss system to make sure that the same teams would not play against each others frequently, but in the last one or two rounds there is a switch to the Danish system, especially to allow the first two ranked teams to battle against each others for the victory, even if they have met before during the tournament.
Konrad system
In a few tournaments which run over a long period of time, such as a tournament with one round every week for three months, a flexible system called a Konrad tournament can be used. A player's final score is based on his best results (e.g. best ten results out of the twelve rounds). Players are not required to play in every round, they may enter or drop out of the tournament at any time. Indeed they may decide to play only one game if they wish to, although if a player wants to get a prizePrize
A prize is an award to be given to a person or a group of people to recognise and reward actions or achievements. Official prizes often involve monetary rewards as well as the fame that comes with them...
they need to play more rounds to accumulate points. The tournament therefore includes players who want to go for a prize and play several rounds as well as players who only want to play an off game. This system is used by a few chess club
Chess club
A chess club is a club formed for the purpose of playing the board game of chess. Chess clubs provide for both informal games and timed games, often as part of an internal competition or in a league.-Organisation:...
s in Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
.
Luton system
In this variation, competitors are paired with a rival on the same score, as usual, but can play the same opponent more than once. Luton is used for small tournaments, where there are too few participants to allow the full Swiss system to work. In most parts of the world better known as "Danish system".McMahon system
A variant known as the McMahon system tournamentMcMahon system tournament
A McMahon system tournament is a generalized case of the Swiss system tournament, used for games such as go and chess.Like a Swiss tournament, all players compete in the same number of rounds against various other players. Unlike Swiss, the players do not all start with zero points, but are awarded...
is the established way in which Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an Go tournaments are run. This differs mainly in that players start at different levels; so the Swiss system is the special case where all players start at the same level. It is named for Lee E. McMahon
Lee E. McMahon
Lee E. McMahon was an American computer scientist. He was a graduate of St. Louis University and obtained a Ph.D. in Psychology at Harvard. He worked for Bell labs from 1963 until 1989, and is best known for his contributions to early versions of the Unix operating system, in particular the sed...
(1931–1989) of Bell Labs
Bell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
.
Monrad system
A common tournament system in Norway and DenmarkDenmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
is the Monrad system. This is very similar to the Swiss System, but deemphasizes ratings, and bases the pairings on the starting number each contestant has received at random before the tournament.
The Danish version is a fairly simple method, players are initially ranked at random, and pairings are modified mainly to avoid players meeting each other twice. The Norwegian system has an optional seeding system for the first round pairings, and within a score group, the pairing algorithm endeavours to give players alternating colors.
Amalfi system
A tournament system in Italy. It is similar to the Swiss System, but doesn't split players based on their score. Before pairing any round, players are listed for decreasing score / decreasing rating, and the opponent of the first player in the list is the player following him by a number of positions equal to the number of remaining rounds, and so on for the other players. As consequence of this, the difference in rating between opponents at the first round is not so big (as for the accelerated systems), and ideally the "big match" between the first and the second one should occur at the last round, no matter how many players and rounds are in the tournament.Badminton
International Student Badminton TournamentsInternational Student Badminton Tournament
International Student Badminton Tournament is a badminton tournament organised for students, by students. They take place all over Europe, in countries including Austria, England, France, Germany, Ireland, the Netherlands, Norway, Poland, Russia and Scotland. ISBT's promote both the sport of...
depend on the Swiss ladder system to ensure its players get as many challenging matches as possible over the course of the badminton
Badminton
Badminton is a racquet sport played by either two opposing players or two opposing pairs , who take positions on opposite halves of a rectangular court that is divided by a net. Players score points by striking a shuttlecock with their racquet so that it passes over the net and lands in their...
tournament. The tournaments are meant to promote both the sport and the social aspect of the game, hence its results are not connected to external rankings. Beforehand, players can enroll in three or four categories designed to separate national, regional and recreational players. Players of different clubs are coupled to form doubles and mix doubles. The starting positions on each ladder (singles, doubles and mix doubles) are random. Unlike in official matches a 1-1 draw is possible and games are usually not extended after 21 is reached in order to maximise the number of played matches.
Bridge
The Swiss system is also used in some bridgeDuplicate bridge
Duplicate bridge is the most widely used variation of contract bridge in club and tournament play. It is called duplicate because the same bridge deal is played at each table and scoring is based on relative performance...
tournament events. They involve teams of four, five, or six players (usually four). In each round, one team plays against another team for several hands, with the north/south pair of the team playing against the east/west pair of the other team. The same hands are played at both tables and each hand is scored by International Match Points (IMPs). The difference in the total IMPs is converted to victory points, with either twenty or thirty victory points split between the two teams, depending on the difference of the IMPs. In the first round, teams are paired essentially randomly. In subsequent rounds, the teams are ranked in order of the number of victory points they have accumulated and the top team plays the second team, the third team plays the fourth team, etc., subject to the proviso that teams do not play each other twice. In the last one ore two rounds there may be a switch to the Danish system to make sure that each team plays the final match according to its actual ranking, even if this results in some teams playing against an opponent they have met already before.
Chess
In chess, each player will be pitted against another player who has done as well (or as poorly) as him or herself. The first round is either drawn at random or seeded according to rating. Players who win receive a point, those who draw receive half a point and losers receive no points. Win, lose or draw, all players proceed to the next round where winners are pitted against winners, losers are pitted against losers and so on. In subsequent rounds, players face opponents with the same (or almost the same) score. No player is paired up against the same opponent twice however. In chess it is also attempted to ensure that each player plays an equal number of games with white and black, alternate colors in each round being the most preferable, and definitely not the same color three times in a row. The basic rule is that players with the same score are ranked according to rating. Then the top half is paired with the bottom half. For instance, if there are eight players in a score group, number 1 is paired with number 5, number 2 is paired with number 6 and so on. Modifications are then made to balance colors and prevent players from meeting each other twice.Debate tabs
British Parliamentary StyleBritish Parliamentary Style
British Parliamentary style debate is a common form of academic debate. It has gained support in the United Kingdom, Ireland, Canada, Europe, Africa, Philippines and United States, and has also been adopted as the official style of the World Universities Debating Championship and European...
debate competitions have four rather than two teams in each debate. The preliminary round for many such competitions, including the World Universities Debating Championship
World Universities Debating Championship
The World Universities Debating Championship is the world's largest debating tournament, and one of the largest annual international student events in the world. It is a parliamentary debating event, held using the British Parliamentary Debate format. Each year, the event is hosted by a university...
, ranks teams by a modified form of Swiss tournament, usually called a tab. "Tab" also denotes to the software used for scheduling of rounds and tabulation of results. Teams are ranked from first to fourth in each debate and awarded from three down to zero points. Teams with similar points totals are grouped off for each successive round. Just as chess Swiss tournaments are arranged to ensure players have a balance of playing with black pieces and white pieces, so too debate tournaments attempt to provide teams with a balance of places in the speaking order (i.e. Opening Government, Opening Opposition, Closing Government, and Closing Opposition). With four competitors rather than two, significantly greater compromise is required to balance the ideal requirements of, on the one hand, a team not meeting the same opponent twice and, on the other hand, a team having a balanced mix of places in the running order.
Magic: the Gathering
The DCI, the tournament sanctioning body for the card game Magic: The GatheringMagic: The Gathering
Magic: The Gathering , also known as Magic, is the first collectible trading card game created by mathematics professor Richard Garfield and introduced in 1993 by Wizards of the Coast. Magic continues to thrive, with approximately twelve million players as of 2011...
, uses a Swiss system for most tournaments. Unlike with other Swiss implementations, players receive three points for a win
Three points for a win
Three points for a win is a standard used in many sports leagues and group tournaments, especially in association football, in which three points are awarded to the team winning a match, with no points to the losing team. If the game is drawn, each team receives one point...
and only one for a draw. After sufficient rounds to produce one undefeated player, typically the top eight players advance to a single-elimination
Single-elimination tournament
A single-elimination tournament, also called a knockout, cup or sudden death tournament, is a type of elimination tournament where the loser of each match or bracket is immediately eliminated from winning the championship or first prize in the event...
stage, with several statistics used as tie-breakers.
Scrabble
In some ScrabbleScrabble
Scrabble is a word game in which two to four players score points by forming words from individual lettered tiles on a game board marked with a 15-by-15 grid. The words are formed across and down in crossword fashion and must appear in a standard dictionary. Official reference works provide a list...
tournaments, a system known variously as "modified Swiss", "Portland Swiss", "Fontes Swiss" or "speed pairing" is used, whereby first players are placed in groups of four, and play three rounds of round-robin play, and subsequently are paired as in Swiss pairing, but using the standings as of the second to last round, rather than the last round. This has the advantage of allowing the tournament directors to already know who plays whom by the time given players are finished with a round, rather than making the players wait until all players have finished playing a given round before being able to start the time-consuming pairing process.
Commonly used in Australia, and now in many other countries, is a system known as "Australian Draw". Whereby each round is paired using a normal #1 plays #2, #3 plays #4, etc. except that repeat pairings within a selected range of previous games is forbidden. Often, for shorter tournaments the selected range will be since the very first round of the tournament, thus never having a repeat pairing for the entire tournament. For longer tournaments it is also common to have the first N rounds use the Australian Draw system, and followed by one or more "King Of the Hill" rounds. "King Of the Hill" is a strict #1 plays #2, #3 plays #4, etc. with no regard to previous pairings, thus unlimited repeat pairings are allowed.
Another Scrabble
Scrabble
Scrabble is a word game in which two to four players score points by forming words from individual lettered tiles on a game board marked with a 15-by-15 grid. The words are formed across and down in crossword fashion and must appear in a standard dictionary. Official reference works provide a list...
system based on Swiss pairing is known as "Chew pairing", and has been used at recent North American National and Canadian National Scrabble championships, and since 2005 at the World Scrabble Championship
World Scrabble Championship
The World Scrabble Championship is the most prestigious title in competitive English-language Scrabble. It has been held every second year since 1991. The current World Scrabble Champion is Nigel Richards...
. Simulations are performed to determine which players are still in contention for each prize and those players are paired so as to balance the right of a low-ranked player to avoid elimination by challenging a high-ranked player with the right of high-ranked players to compete directly with each other for prizes.
Ultimate Frisbee
Windmill Windup, a three-day yearly tournament in Ultimate Frisbee held in Amsterdam was the first event in ultimate to introduce the Swiss draw system into the sport in 2005. In later years many other tournaments started using this format like Belgium's G-spot, Wisconsin Swiss and many others.In ultimate frisbee it works like this: for each round, the teams earn victory points based on the score difference of their win (or loss). In this way, also a team clearly losing a game is encouraged to fight for every point in order to get more victory points. After each round, teams are ranked according to their victory points. Ties are broken by considering the sum of the current victory points of their opponents. In the next round, neighboring teams in the ranking play each other. In case they have played each other in a previous round, adjustments to the rankings are made. After five rounds of Swiss draw, three playoff rounds (in groups of 8) are played to determine the final placement of the teams. See Swiss Draw in Ultimate Frisbee for more details.
See also
- Tie-breaking in Swiss system tournamentsTie-breaking in Swiss system tournamentsTie-break systems are used in chess Swiss system tournaments to break ties between players who have the same total number of points after the last round. If the players are still tied after one tie-break system is used, another system is used, and so on, until the tie is broken...
Other tournament systems:
- Round-robin tournamentRound-robin tournamentA round-robin tournament is a competition "in which each contestant meets all other contestants in turn".-Terminology:...
- Single-elimination tournamentSingle-elimination tournamentA single-elimination tournament, also called a knockout, cup or sudden death tournament, is a type of elimination tournament where the loser of each match or bracket is immediately eliminated from winning the championship or first prize in the event...
- Double-elimination tournamentDouble-elimination tournamentA double-elimination tournament is a type of elimination tournament competition in which a participant ceases to be eligible to win the tournament's championship upon having lost two games or matches...
- Scheveningen systemScheveningen systemThe Scheveningen system is a method of organizing a chess match between two teams. Each player on one team plays each player on the other team . The team with the highest number of games won is the winner. This system is a popular way to create title norm opportunities.The system was first used...