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Chankan: Difference between revisions
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{{Yaku compatibility table|CHK}} | {{Yaku compatibility table|CHK}} | ||
Excluding kokushi musou, chankan requires at least one sequence | Excluding kokushi musou, chankan requires at least one sequence, because waits to complete a pair (tanki) or triplet (shanpon) would be impossible. This excludes [[toitoi]], [[chiitoitsu]], and [[honroutou]]. [[Ryanpeikou]] is also not allowed, due to the tile requirement. A ryanpeikou tenpai would require at least one copy of the winning tile, which prevents the other players from calling kan. | ||
As for [[rinshan]], [[haitei]], [[houtei]], and [[mentsumo]], it is physicially impossible to combine any of these four with chankan. Rinshan, mentsumo, and haitei require a win by self draw, while chankan is always won with ron. In the case of houtei, a player is not allowed to call kan if there are no tiles left in the live wall, so a chankan cannot be the last discard. | As for [[rinshan]], [[haitei]], [[houtei]], and [[mentsumo]], it is physicially impossible to combine any of these four with chankan. Rinshan, mentsumo, and haitei require a win by self draw, while chankan is always won with ron. In the case of houtei, a player is not allowed to call kan if there are no tiles left in the live wall, so a chankan cannot be the last discard. | ||
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=== Ippatsu === | === Ippatsu === | ||
The [[ippatsu]] yaku is normally interrupted by a kan call. To call chankan, the opposing player had already called for kan. However, ippatsu is still not interrupted because the whole kan process has not been completed. The entire kan process includes the kan call itself, plus the rinshan draw and the discard afterwards. The chankan win occurs in the middle of that process. So, it is allowable to score both ippatsu and chankan at the same time. | The [[ippatsu]] yaku is normally interrupted by a kan call. To call chankan, the opposing player had already called for kan. However, ippatsu is still not interrupted because the whole kan process has not been completed. The entire kan process includes the kan call itself, plus the rinshan draw and the discard afterwards. The chankan win occurs in the middle of that process. So, it is allowable to score both ippatsu and chankan at the same time. | ||
=== Double Riichi === | |||
Chankan requires an added kan, which itself requires a pon. This invalidates double riichi for any regular hand: | |||
* If a pon is made before the riichi call, double riichi is negated. | |||
* If the pon call happens after the riichi call, then the double riichi player must have declined their winning tile, invoking [[furiten]]. Since chankan can only be won off ron, furiten makes this yaku impossible. | |||
However, an exception exists with [[kokushi musou]]. Depending on [[Kokushi_musou#Chankan_rule_variation|rule variation]], kokushi may be won off a [[ankan|closed kan]], which does not require a previous pon call. Therefore, in order to win with double riichi + chankan, it must also have kokushi. Since this would be a yakuman hand, neither double riichi or chankan would actually be scored. | |||
== Special cases == | == Special cases == | ||