A

tournament or all-play-all tournament is a type of tournament "in which each contestant meets every other contestant in turn".[1] In a single

schedule, each participant plays every other participant once. If each participant plays all others twice, this is frequently called a double

. 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 almost all of the major United States professional sports leagues - see AFL III and All America Football Conference for exceptions).
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