A round-robin tournament or all-play-all tournament is a type of group tournament in which each participant plays every other participant an equal number of times. In a pure round-robin schedule, each participant plays every other participant once. If each participant plays all others twice, this is frequently called a double round-robin. The term is rarely used when all participants play one another more than twice, and is never used when one participant plays others an unequal number of times (as is the case in all of the major United States professional sports). A tournament is an organized competition in which many participants play each other in individual games. ...

The term round robin is derived from the French term ruban meaning ribbon. Over a period of long time the term got corrupted and idiomized to robin. see: round robin. The term round-robin is used in several contexts and usually means that a number of things are taking turns at something, for example a round-robin-party where participants walk door to door for small parties at each participants habitat. ...

In sports with a large number of competitive matches per season, double round-robins are common. Almost all football (soccer) leagues in the world are organized on a double round-robin basis, in which every team plays all others in its league once at home and once away. There are also round-robin chess tournaments; the World Chess Championship was decided in 2005, and will again be decided in 2007, in an eight-player double round-robin tournament, where each player faces every other player once as white and once as black. Football (soccer) - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... Chess is an abstract strategy board game and mental sport for two players. ... The World Chess Championship is played to determine the World Champion in the board game chess. ...

Group tournaments rankings usually go by number of matches won and drawn, with any of a variety of tiebreaker criteria. A tournament is an organized competition in which many participants play each other in individual games. ...

Frequently, pool stages within a wider tournament are conducted on a round-robin basis. Examples with pure round-robin scheduling include the FIFA World Cup and UEFA Cup (since 2004–05) in soccer, the National Provincial Championship of rugby union in New Zealand, the Cricket World Cup and many American Football college conferences, such as the Mountain West Conference. The group phase of the UEFA Champions League is contested as a double round-robin, as are most basketball leagues outside the United States, including the regular-season and Top 16 phases of the Euroleague. A tournament is a competition involving a relatively large number of competitors, all participating in a single sport or game. ... The FIFA World Cup Trophy, which has been awarded to the world champions since 1974. ... The UEFA Cup is a football competition for European club teams, organized by the Union of European Football Associations (UEFA). ... 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... The National Provincial Championship (which for sponsorship reasons, is referred to as Air New Zealand NPC or just simply NPC) is New Zealands principal domestic rugby union competition. ... General phase play in rugby union. ... Cricket World Cup 2007 logo The ICC Cricket World Cup is the premier international championship of one-day cricket in the world. ... United States simply as football, is a competitive team sport that is both fast-paced and strategic. ... This is a list of athletic conferences of the National Collegiate Athletic Association (NCAA) and National Association of Intercollegiate Athletics (NAIA). ... The Mountain West Conference (or MWC), the youngest of the College Athletic Conferences affiliated with the NCAA’s Division I-A, officially began operations in July 1999. ... The UEFA Champions League (known colloquially as the European Cup) is an annual club football competition organised by the Union of European Football Associations (UEFA) for the most successful football clubs in Europe. ... Sara Giauro shoots a three-point shot, FIBA Europe Cup for Women Finals 2005. ... The Euroleague is a high-caliber professional basketball league with teams from all over Europe. ...

Evaluation

In a round-robin format, the element of luck is seen to be reduced, given that all competitors face the same opponents, and a few bad performances need not cripple a competitor's chances of ultimate victory. In English football, although the FA Cup was founded before the Football League, the (round-robin) League champions have always been regarded as the "best" team in the land, rather than the (knockout) Cup winners. Football is the unofficial national sport of England, and as such has an important place within English national life. ... The FA Cup - this is the fourth trophy, in use since 1992, and identical in design to the third trophy introduced in 1911. ... The Football League is an organisation representing 72 professional football clubs in England and Wales, and runs the oldest professional football league competition in the world. ... A single-elimination tournament, also called a knockout tournament, is a type of tournament where the loser of each match is immediately eliminated from winning the championship or first prize in the event. ...

Disadvantages include the existence of games late in the competition between competitors with no remaining chance of success. Moreover, some later matches will pair one competitor who has something left to play for against another who does not. This asymmetry means that playing the same opponents is not necessarily equitable: the same opponents in a different order may play harder or easier matches. There is also no showcase final match. The ability to recover from defeats, while rewarding overall consistency, may also be seen as a crutch for competitors who lack the temperament to handle the pressure of a knockout tournament.

Further issues arise where a round-robin is used as a qualifying round within a larger tournament. A competitor already qualified for the next stage before its last game may either not try hard (in order to conserve resources for the next phase) or even deliberately lose (if the scheduled next-phase opponent for a lower-placed qualifier is perceived to be easier than for a higher-placed one).

Swiss system tournaments attempt to combine elements of the round-robin and elimination formats, to provide a reliable champion using within fewer rounds than a round-robin, while allowing draws and losses A Swiss system tournament is a commonly used type of tournament in chess and other games where players or teams need to be paired to face each other. ...

Scheduling Algorithm

If n is the number of competitors, a pure round robin tournament requires games. If n is even, then in each of (n − 1) rounds, games can be run in parallel, provided there exist sufficient resources (e.g. courts for a tennis tournament). If n is odd, there will be n rounds with games, and one competitor having no game in that round. A tennis net Tennis is a sport played between either two players (Singles) or two teams of two players (doubles). Players use a stringed racquet to strike a hollow rubber ball covered with felt over a net into the opponents court. ...

The standard algorithm for round-robins is to assign each competitor a number, and pair them off in the first round … Flowcharts are often used to represent algorithms. ...

 Round 1. (1 plays 14, 2 plays 13, ... ) 1 2 3 4 5 6 7 14 13 12 11 10 9 8 

… then fix one competitor (number one in this example) and rotate the others clockwise …

 Round 2. (1 plays 13, 14 plays 12, ... ) 1 14 2 3 4 5 6 13 12 11 10 9 8 7 

 Round 3. (1 plays 12, 13 plays 11, ... ) 1 13 14 2 3 4 5 12 11 10 9 8 7 6 

… until you end up almost back at the initial position

 Round 13. (1 plays 2, 3 plays 14, ... ) 1 3 4 5 6 7 8 2 14 13 12 11 10 9 

If there are an odd number of competitors, a dummy competitor can be added, whose scheduled opponent in a given round does not play and has a bye. The upper and lower rows can indicate home/away in sports, white/black in chess, etc (this must alternate between rounds since competitor 1 is always on the first row). If, say, competitors 3 and 8 were unable to fulfill their fixture in the third round, it would need to be rescheduled outside the other rounds, since both competitors would already be facing other opponents in those rounds. More complex scheduling constraints may require more complex algorithms. Dummy may refer to: A mannequin The figure used by a ventriloquist A babys dummy – the British English equivalent word for a pacifier Something that is not real; a forgery Something that features certain aspects of a real object that require repeated or straining exposure to testing, but does... A bye is when a player or team is allowed to advance to the next round of a playoff tournament without playing. ... Chess is an abstract strategy board game and mental sport for two players. ...

External links

• SCHED link to a DOS program to quickly create round robin schedules