Chankan: Difference between revisions

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With one exception, in order for chankan to occur:
With one exception, in order for chankan to occur:
* You must be in [[tenpai]], waiting on a tile an opponent already called [[pon]] for. Any tenpai hand can win with chankan, even if the hand would be "yakuless" otherwise.
* You must be in [[tenpai]], waiting on a tile an opponent has already called [[pon]] for. Any tenpai hand can win with chankan, even if the hand would be "yakuless" otherwise.
* The opponent must draw the 4th copy of the ponned tile, then declare a shouminkan (added kan) with it.  
* The opponent must draw the 4th copy of the ponned tile, then declare a shouminkan (added kan) with it.  


Only shouminkans are vulnerable to chankan (again with one exception):
The exception is with [[kokushi musou]]. A hand in tenpai for kokushi musou is allowed to call ron on a closed kan. Not all rulesets allow kokushi to ron a closed kan.
*[[Ankan]] (closed kan) cannot be ronned. The exception is if a hand is in tenpai for [[kokushi]]. A kokushi hand may call ron on an ankan. Not all rulesets enable this "kokushi chankan on a closed kan" rule, though.
*It is impossible to ron off an [[Kan#Daiminkan|daiminkan]] (open kan). When a tile is discarded, it can either be used for ron, or it can be used to complete the kan. Ron takes precedence over kan, so the player wins before the kan is made. If the ron call is skipped, you cannot retroactively ron after the kan is made.


Because the opponent must have had possession of all 4 copies of the winning tile, it is impossible for you to have another copy of that tile.
Chankan can only happen to added kans. Closed kans cannot be ronned, except for the kokushi case described above. It would be impossible to ron an open kan, since when a tile is discarded, it can be used for eiher ron or open kan. Ron takes precedence over kan, so the player wins before the kan is made. If the ron call is skipped, you cannot retroactively ron after the kan is made.


Chankan interrupts the call for kan before it starts. This means that [[kandora]] are not revealed after chankan, and chankan denies the opponent's [[rinshan]] draw.
Chankan interrupts the call for kan before it starts. This means that [[kandora]] are not revealed after chankan, and chankan denies the opponent's [[rinshan]] draw.


===Machi===
==Wait==
{{main|Machi}}
{{main|Machi}}
As mentioned above, in order to obtain chankan, it is impossible to have a copy of the given winning tile in your hand. Therefore, [[wait]]s involving [[shanpon]] or [[tanki]] are impossible. If you hold a tile in your hand, the opponent cannot make an added kan, making it impossible to chankan with that tile. Therefore, only three of the basic waits are possible: [[penchan]], [[kanchan]], and [[ryanmen]]. These are all waits to complete a [[sequence]].
Because the opponent must have had possession of all 4 copies of the winning tile, it is impossible for you to have another copy of that tile. This means that [[shanpon]] and [[tanki]] waits are not compatible with this yaku.
 
Therefore, the only basic waits available are [[penchan]], [[kanshan]], and [[ryanmen]]; all three are waits to complete a [[sequence]].


In the case for [[kokushi musou]], the hand will be tenpai for kokushi with one of the 13 tile types already paired, and it is waiting for the last tile type for completion. Depending on the ruleset, kokushi may or may not be allowed to win from a closed kan.
In the case for [[kokushi musou]], the hand will be tenpai for kokushi with one of the 13 tile types already paired, and it is waiting for the last tile type for completion. Depending on the ruleset, kokushi may or may not be allowed to win from a closed kan.


===Furiten===
===5th kan draw===
Chankan can only happen when a player calls pon. Therefore, there is at least one player who will be in [[furiten]] for chankan, and that is the player who was used to complete the original pon call.
When a player is in tenpai for [[suukantsu]], some [[rule variations]] allow calling a fifth kan to invoke a 4th kan draw. If a fifth kan is allowed in this way, chankan might not apply - the game (usually) ends before a chankan can happen.
 
===Limitation===
When a player is in tenpai for [[suukantsu]], some [[rule variations]] allow invoking a fifth kan to cause a draw. If a fifth kan is allowed in this way, chankan may not apply - the game ends before a chankan can happen.


== Compatibility ==
== Compatibility ==
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{{Yaku compatibility table|CHK}}
{{Yaku compatibility table|CHK}}


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.
Chankan requires at least one sequence (excluding kokushi), 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 physically 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 physically 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".


=== Ippatsu ===
=== Ippatsu ===
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