Round-robin tournament
As a round-robin tournament (also Round Robin, Round Robin or English league system ) is a type of tournament or a league mode indicates where each tournament participants equally often competes against all the other tournament participants.
This system will, inter alia, in most soccer leagues applied by reference to a solid game plan every team against every other team once at home and once away plays (exact name: Double Round Robin, that is a double round-robin tournament, as each team each outperforms other twice).
Assessment
The round-robin tournament, in particular the double round-robin tournament, is generally regarded as equitable famous system; in fact, it provides a theoretically correct continuous ranking from first to last place.
In a einrundigen tournament each of the n participants meet once on each of the n - 1 other participants, so that n - 1 rounds (or n rounds with an odd number of participants) and a total of n · ( n - 1 ) / 2 games are played. Thus, such contests can be conducted over a longer period through. In a double round-robin tournament, there are twice as many, namely n · ( n - 1) Games.
The shape of the double- round tournament is not only in team tournaments with change of location where the venue has a certain advantage, applied, but also about chess, where the number of participants is limited. That's not at every round of a pause must, the number of participants is usually straight. In a tournament with an even number of participants einrundigen half must often play with the black pieces, while the other half once again has white, which is a certain advantage once. Nevertheless chess tournaments are often played einrundig so that they are never quite live up unless the number of participants is odd. The same problem arises again at football tournaments in terms of home advantage. In the einrundigen to 2009 group stage of the UEFA Cup one was by her fair that each group had an odd number of participants, namely five.
In a pure round-robin tournament meet in general, the top two not only in the final round each other. Therefore, the decision about winning the title falls very often before the last round, so the Games are no longer interested cause, which of course is not desirable from the perspective of the organizer.
If the decision about the title really only in the last round, so are usually a so-called " distance duel " the rash and no direct comparison. In this way " kingmaker " arise constellations, but also the possibility of collusion (as the one observed in the candidates tournament for the World Chess Championship ).
After completing all rounds, it is possible that two players or teams are placed on a par, so that here fine Ratings ( tie- breakers ) must be applied. In some cases, the result of the mutual match is used for this; However, there are a variety of methods in use, such as:
- In chess: Various forms of fine rating,
- In team sports: points from direct matches, goal difference, number of goals scored, number of goals, etc.
- Or own play-off games that can be performed on the regular rounds in the port. The play-off matches will be held in turn by the knockout system, so this results is a mixed tournament format.
Implementation
If the number is a participant, a pure round-robin tournament requires games. If is even, can be played simultaneously in each of the rounds of games, provided there are enough playgrounds. If is odd, there are rounds on games, and a counterparty without a game in this round.
- The usual procedure for a round-robin tournament is to assign a number to each participant, and to remove the encounters each round of so-called pairing boards (English Berger pairing tables ) ( see example in the links).
- For games in which the participants in pairs sit at a table set against, the slip system is an easy working procedure to host a tournament round.
Modifications
In many cases, a combination of knockout and round robin system is employed. See tournament form.