League

A league has a specific meaning in the context of the big titles of professional Go, especially in Japan. It refers to the round-robin (all-play-all) used to determine the challenger who will play the incumbent (reigning) champion. Some leagues use other formats, such as the Swiss system.

• International
  • World Supreme Player
• Korea
  • GS Caltex Cup
• Japan
  • Meijin league
  • Kisei league (its C league is not a round-robin; it uses a modified Swiss system pairings)
  • Women's Meijin
  • Teikei Cup Shun'ei

Often, the league players are selected based upon two criteria: the top finishers of last year's league for the title and the winners of a set of single knockout tournaments. (Example: The Honinbo League consists of eight players: four are the top finishers of last year's Honinbo League; four are the winners of four distinct single knockout tournaments each open to one quarter of all professionals recognized by a Japanese certifying organization (Nihon Kiin or Kansai Kiin).

To win an all-play-all league, you must play well with either color, Black or White. In knockout tournaments, colors are decided randomly by nigiri each game and a lucky player may get his favorite color in nearly all games. Such a fluke can't occur in all-play-all format.

Team league

Many countries have team leagues in round robin format, such as China Weiqi League, Korean Baduk League and German Go Bundesliga. It's a convenient format for sponsors seeking some publicity because sponsoring a team is less costly and more flexible than sponsoring a whole tournament.