Chankan: Difference between revisions

'''Chankan''' {{kana|搶槓}} is a standard yaku.  It is dependent on the usage of [[kan]], where a player may declare ron while a player calls to upgrade a [[koutsu|minkou]] (triple called via [[pon]]) to a [[Kan#Shominkan|shominkan]] (added kan).  In other words, if a player is tenpai for a tile used for that specific added kan, then the player may declare a win on that tile.

 

==Hand pattern==

Alternatively, this yaku may be referred to as "robbing a kan".  [[Tenpai]] for chankan must involve a hand, in which one of the [[machi|waiting tiles]] has been called as [[naki|pon]] by another player. Any tenpai hand works for chankan, even if the hand is otherwise yakuless.  As long as the waiting tile has been called for [[naki|pon]] earlier and then the player calls for an added kan, this creates a time for a player to claim the added tile for a win. Naturally, waits involving [[jihai|honor tiles]] do not work in this situation.

While the call for kan reveals additional [[dora]], in the form of kan-dora, the call for chankan interrupts the process for kan.  Therefore, additional dora is not revealed.

 

==Machi==

 

So, when it comes to [[machi]] (wait patterns), only three basic types can be used for chankan: [[penchan]], [[kanchan]], and [[ryanmen]]. To achieve chankan, all four copies of a tile would have needed to been in another player's hand. Therefore, a hand winning with chankan must not have any other copies of the winning tile. This forbids tile patterns involving [[shanpon]] and [[tanki]], as these waits require another copy of the tile.

Under any possible instance of chankan, one player is barred from calling ron and awarded this yaku due to [[furiten]].  The initial tile discard was granted for the open call for pon.

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.

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.

== Special cases ==

 

If the rules allow, a special case for [[kokushi musou]] exists.  This involves a kokushi tenpai hand, where the final tile may be completed with an opponent calling [[kan]] with a closed kan using all four of that particular winning tile.  Thus, ron may be declared in that instance, involving the special chankan rule.  This is the only case where a tile may be taken from an closed kan.  However, this particular rule may be [[Yaku_variations#Kokushi_and_chankan|subject to variation]], which may or may not allow the play to occur.