A double-elimination tournament is a type of elimination tournament

Elimination tournament

Elimination tournament may refer to any of several types of tournament in which each player has a set number of loses before elimination from the competition.*Single-elimination tournament, in which a player is eliminated after losing to a single opponent...

 competition

Competition

Competition is a contest between individuals, groups, animals, etc. for territory, a niche, or a location of resources. It arises whenever two and only two strive for a goal which cannot be shared. Competition occurs naturally between living organisms which co-exist in the same environment. For...

 in which a participant ceases to be eligible to win the tournament

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:...

's championship upon having lost two games or matches. It stands in contrast to a single-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...

, in which only one defeat results in elimination.

A double-elimination tournament is broken into two sets of brackets

Bracket (tournament)

A bracket is a tree diagram that represents the series of games played during a tournament, named as such because it appears to be a large number of interconnected brackets....

, the Winners Bracket and Losers Bracket (W and L Brackets for short; also sometimes Upper Bracket and Lower Bracket, respectively). After the first round, the winners proceed into the W Bracket and the losers proceed into the L Bracket. The W Bracket is conducted in the same manner as a single-elimination tournament, except of course that the losers of each round "drop down" into the L Bracket.

As with single-elimination tournaments, most often the number of competitors is equal to a power of 2 (8, 16, 32, etc.) so that there are an even number of competitors at every round. The maximum number of games in a double elimination tournament is one less than twice the number of teams participating (e.g., 8 teams - 15 games). The minimum number is two less than twice the number of teams (e.g., 8 teams - 14 games).

Conducting the tournament

Each round of the L Bracket is conducted in two stages, the first stage consisting of the winners of the previous stage (or losers of the very first round of competition) playing their matches, the second stage consisting of the winners of the first stage against the losers of that same round of the W Bracket playing their matches. This is to allow the losers of each stage of the W Bracket to "filter down" into the L Bracket.

For example, in an eight-competitor double-elimination tournament, the losers of the first round enter the first stage of the L Bracket – the L Bracket quarterfinals – and compete against each other. The losers are eliminated, while the winners proceed to the second stage of the L Bracket – the L Bracket semifinals – to face the losers of the W Bracket semifinals. The winners of the L Bracket semifinals proceed to the L Bracket finals, with the winner of that game being the Losers' Bracket champion.

The championship finals of a double elimination tournament is usually set up to be a possible two games. The rationale is that since the tournament is indeed double elimination, it is unfair to have the Winners' Bracket champion eliminated with its first loss. Therefore, while the Winners' Bracket champion needs to beat the Losers' Bracket champion only once to win the tournament, the Losers' Bracket champion must beat the Winners' Bracket champion twice.

In some tournaments, however, the final game is always winner-take-all, or always a best-of-three set of games, with the usual advantage of the last Winner's Bracket team ignored.

Pros and cons

The double-elimination format has some advantages over the single-elimination format, most notably the fact that third and fourth places can be determined without the use of a consolation or "classification" match involving two contestants who have already been eliminated from winning the championship. Additionally, in a double-elimination format better teams are likely to progress further in the tournament. Suppose in a single-elimination tournament the best team plays the second best team in the first round—the second best team will be eliminated right away, having only played one game. Then, a more mediocre team with a more favorable seeding could potentially win several games, play the best team in the finals, and come away with second place. (Usually, good seeding would help avoid this, but it is an issue nonetheless.) A double-elimination tournament would allow the second best team to keep winning (in the loser's bracket) and eventually work their way back up to their rightful position of second place.

A disadvantage compared to the single-elimination format is that a considerably greater number of matches have to be conducted: since each player has to lose twice and since the tournament ends when only one player remains, in tournament for N competitors there will be (or in case the winner was undefeated during the tournament) games; a plausible alternative is a single-elimination format where each match is a best-of-5 or best-of-7 series. This format still allows a competitor to lose (perhaps multiple times) while still remaining eligible to win the tournament. Of course, having multiple games in each series also requires considerably more games to be conducted. The fact that the final game in the tournament may be unnecessary is also a disadvantage, particularly if broadcasting and ticket sales companies have an interest in the tournament.

The best-known athletic event that employs a double-elimination format is the NCAA baseball tournament, including the College World Series

College World Series

The College World Series or CWS is an annual baseball tournament held in Omaha, Nebraska that is the culmination of the NCAA Division I Baseball Championship, which determines the NCAA Division I college baseball champion. The eight teams are split into two, four-team, double-elimination brackets,...

, where a team is not eliminated until it loses twice in each of the four rounds (regional, super regional, College World Series, and CWS championship, with the super regional and CWS championship series featuring two teams in a best 2-of-3 format). It is also extensively used in computer gaming tournaments (most famously by the Cyberathlete Professional League

Cyberathlete Professional League

The Cyberathlete Professional League , founded on June 27, 1997 by gaming entrepreneur Angel Munoz, is a professional sports tournament organization specializing in computer and console video game competitions....

) and table football

Table football

Table football, also known as gitoni or foosball, is a table-top game and sport that is loosely based on association football.-Names:...

 tournaments. Double-elimination brackets are also popular in amateur wrestling

Amateur wrestling

Amateur wrestling is the most widespread form of sport wrestling. There are two international wrestling styles performed in the Olympic Games under the supervision of FILA : Greco-Roman and freestyle. Freestyle is possibly derived from the English Lancashire style...

 of all levels, surfing

Surfing

Surfing' is a surface water sport in which the surfer rides a surfboard on the crest and face of a wave which is carrying the surfer towards the shore...

 and kiteboarding freestyle competitions, as well as Curling

Curling

Curling is a sport in which players slide stones across a sheet of ice towards a target area. It is related to bowls, boule and shuffleboard. Two teams, each of four players, take turns sliding heavy, polished granite stones, also called "rocks", across the ice curling sheet towards the house, a...

 bonspiel

Bonspiel

A bonspiel is a curling tournament, traditionally held outdoors on a frozen freshwater loch. The word comes from the Scottish Gaelic and means league match . Though not mandatory, curling teams involved in bonspiels often wear theme costumes...

s (where triple-elimination is also used) and certain Olympic

Summer Olympic Games

The Summer Olympic Games or the Games of the Olympiad are an international multi-sport event, occurring every four years, organized by the International Olympic Committee. Medals are awarded in each event, with gold medals for first place, silver for second and bronze for third, a tradition that...

 sports, such as judo

Judo

is a modern martial art and combat sport created in Japan in 1882 by Jigoro Kano. Its most prominent feature is its competitive element, where the object is to either throw or takedown one's opponent to the ground, immobilize or otherwise subdue one's opponent with a grappling maneuver, or force an...

. Since 2009, the World Baseball Classic

World Baseball Classic

The World Baseball Classic is an international baseball tournament sanctioned by the International Baseball Federation and created by Major League Baseball , the Major League Baseball Players Association , and other professional baseball leagues and their players associations around the world...

 has used a double-elimination format for the first and second rounds of the tournament. The Little League World Series

Little League World Series

The Little League Baseball World Series is a baseball tournament for children aged 11 to 13 years old. It was originally called the National Little League Tournament and was later renamed for the World Series in Major League Baseball. It was first held in 1947 and is held every August in South...

 also switched from round-robin

Round-robin tournament

A round-robin tournament is a competition "in which each contestant meets all other contestants in turn".-Terminology:...

 to double-elimination formats for each of its pools starting in 2010

2010 Little League World Series

-Pool A:-Pool B:-Pool C:-Pool D:-Championship games:-Champions path:The Edogawa Minami LL reached the LLWS with a record of 8 wins, 1 loss, and 1 tie. In total, their record was 13–1–1, their only loss coming against Musashi-Fuchu....

 in an effort to eliminate meaningless games.

It is also used, in modified form, in the All-Ireland Senior Gaelic Football Championship

All-Ireland Senior Football Championship

The All-Ireland Senior Football Championship, the premier competition in Gaelic football, is a series of games organised by the Gaelic Athletic Association and played during the summer and early autumn...

 and All-Ireland Senior Hurling Championship

All-Ireland Senior Hurling Championship

The GAA Hurling All-Ireland Senior Championship is an annual hurling competition organised by the Gaelic Athletic Association since 1887 for the top hurling teams in Ireland....

.

Variations

Some variations on double elimination are used. For example, in Judo, players that end up in the L bracket can finish third at best. The winner of the W bracket will win the tournament, with the losing finalist finishing second. The other losers of the W bracket will end up in the L bracket, which will only be played to the first stage of the final, resulting in two 3rd placed players. Thus, compared to the standard double elimination, there is no second stage of the final of the L bracket played, and there is no game between the winners of the W and L bracket.

Another aspect of the system used in Judo is that losers of the first round (of the W bracket) only advance to the L bracket if the player they lost to wins his or her second round match. If a player loses to a second round loser, they are eliminated from the tournament.

Another variant, called the (third-place) challenge, is used, particularly in scholastic wrestling. The winner of the L bracket may challenge the loser of the finals in the W bracket, if and only if the two contestants had not faced each other previously; if the challenger (the winner of the L bracket) wins, he is awarded second place, and the loser of the W final is dropped to third place. This system is used particularly where the top two places advance to a higher level of competition (example: advancement from a regional tournament to a state tournament).

Another is the balanced variant which is a bracket arrangement that is not strictly divided into two brackets based on number of losses. Players with different numbers of losses can play each other in any round. A goal of the variant is that no player sits idle for more than one round consecutively. The added complexity of the brackets is handled by using "if necessary" matches. The flexible approach allows practical bracket designs to be made for any number of competitors including odd numbers (9, 10, 11, 12, 13, etc.).

The College World Series has frequently tried to modify the double-elimination format to set up, if possible, a single championship game. Until 1988, the College World Series did this by adding an extra round to the Losers' Bracket. What would be the Losers' Bracket semifinals (i.e., the round where the Winners' Bracket semifinal losers dropped down) became the Losers' Bracket quarterfinals, with the Losers' Bracket semifinals having the two participants in the Winners' Bracket final (i.e., the WINNERS of the Winners' Bracket semifinals) drop down. This thus left open the possibility that the Winners' Bracket champion would pick up a loss, albeit in the Losers' Bracket semifinal. If, however, the Winners' Bracket champion prevailed in the Losers' Bracket semifinal, the same two-game final setup existed in effect, albeit not in practice ... for under the CWS pre-1988 version, the unbeaten Winners' Bracket champion would be playing a once-beaten Losers' Bracket opponent in the Losers' Bracket final, with the winner to advance to play the unbeaten Winners' Bracket champion in the finals (if necessary). The CWS subsequently broke up its eight-team field into two four-team double elimination tournaments, with the winners meeting in either a sudden-death or, currently, a best-of-three final.

A way to reduce the number of rounds is to do cross-bracket elimination in the last rounds. For instance, in a double-elimination tournament of eight teams, you could have both the winner and the loser of the Upper Bracket final join the third round of the Lower Bracket, the winner facing the lowest-seeded Loser's Bracket team. If the Winner's Bracket team wins, there will be two teams left and they will go straight to the finals (with the Winner's Bracket team having a one game advantage as usual). However, if the Winner's Bracket team loses then three teams will still be in the tournament, all with one loss. Usually in the subsequent fifth round either the last Winner's Bracket team that just lost has 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...

 round or the top seed remaining will have a bye, while the other two teams square off. This leaves two teams for a one game final in the sixth and last round. Whether the Winner's Bracket team wins or loses in round four, this cross-bracket procedure shortens an eight team double elimination tournament from 6-7 rounds to 5-6 rounds.

Other tournament systems

Variations of the double-elimination tournament include:

• Elimination tournament
  Elimination tournament
  Elimination tournament may refer to any of several types of tournament in which each player has a set number of loses before elimination from the competition.*Single-elimination tournament, in which a player is eliminated after losing to a single opponent...
  
  
• Single-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...
  
  

Other common tournament types are

• Round-robin tournament
  Round-robin tournament
  A round-robin tournament is a competition "in which each contestant meets all other contestants in turn".-Terminology:...
  
  
• Swiss system tournament
  Swiss system tournament
  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...
  
  
• Playoffs - a variation of the single-elimination tournament where instead of one win, a team needs to win a specific number of games in a series in order to advance.