Chankan: Difference between revisions

Chankan
Type	Yaku
Kanji	搶槓
English	Robbing a kan
Value	1 han
Speed	Dependent
Difficulty	Very hard

VisualWikitext

Latest revision as of 02:35, 11 September 2024

Chankan 「搶槓」 is a yaku scored when "robbing a kan". When an opponent upgrades an open triplet into an added kan, you may call ron if the kan would be your winning tile, scoring chankan in the process.

Development

Chankan example, where the player declared ron on 1-pin and all four are shown as a kan.

With one exception, in order for chankan to occur:

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 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.

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.

Wait

Main article: Machi

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, kanchan, 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.

5th kan draw

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.

Compatibility

Main article: Yaku compatibility

^ Ippatsu requires riichi to be of any use.

	RCH	DRI	IPP	SMO	TAN	PFU	IPK	ITT	YAK	SDJ	SDO	TOI	SNA	SNK	CHA	JUN	RPK	SSG	HRO	HON	CHN	CHI	RIN	HAI	HOU	CHK
CHK

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".

Ippatsu

The ippatsu yaku is normally interrupted by a kan call, and chankan requires an opponent to call 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 ippatsu and chankan can be scored together.

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 rule variation, kokushi may be won off a 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.

Kokushi musou variation

If the rules allow, a special case for kokushi musou exists. When a kokushi hand is in tenpai, it may win if an opponent calls a closed kan for the tile you are winning for. Thus, ron may be declared, invoking this special rule. This is the only case where a tile may be taken from an closed kan.

However, this particular rule may be subject to variation, which may or may not allow this play to occur.

External links

搶槓

Chankan in Japanese Wikipedia

@@ Line 11: / Line 11: @@
 * [http://tenhou.net/0/?log=2015032605gm-0089-0000-70f97ed2&tw=0 Chankan baiman]
 }}
-'''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.
+'''Chankan''' {{kana|搶槓}} is a [[yaku]] scored when "robbing a kan". When an opponent upgrades an [[minkou|open triplet]] into an [[Kan#Shominkan|added kan]], you may call [[ron]] if the kan would be your winning tile, scoring chankan in the process.
-In almost all cases, players are not allowed to call ron on an [[Kan#Ankan|ankan]] (closed kan). The notable exception involves a [[kokushi]] [[tenpai]] hand, where the last tile needed for the yakuman is called for an ankan.  However, the kokushi exception varies on the rules.  In [[Rule_variations#Kokushi_and_chankan|some rules]], it is disallowed outright.
+==Development==
-==Hand pattern==
 [[image:Chankan.png|250px|thumb|[http://tenhou.net/0/?log=2012112813gm-0009-7447-af4e435f&tw=2&ts=8 Chankan example], where the player declared ron on 1-pin and all four are shown as a kan.]]
-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 for an otherwise "yakuless" hand.  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.
+With one exception, in order for chankan to occur:
+* 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.
-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.
+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.
-===Limitation===
+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.
-If a player is tenpai for [[suukantsu]] and a fifth kan is invoked, chankan may not be applied if that fifth kan is an added kan.
+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}}
+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.
-As defined, chankan can only be achieved when a [[minkou]] (open triplet) is upgraded to a ''shouminkan''.  In other words, a player had called pon earlier and then drew the 4th tile, for the kan.  If another player is tenpai for that tile, then the player may declare ron.  To some degree, the added kan may be viewed as a discard in this case.
+Therefore, the only basic waits available are [[penchan]], [[kanchan]], and [[ryanmen]]; all three are waits to complete a [[sequence]].
-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.
+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 is tenpai for kokushi with one of the 13-tile types already paired; and it is waiting for the last tile type for completion.  An exception to kan calls involving [[ankan]] (closed kan) is made.
+===5th kan draw===
+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.
-===Furiten===
-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.
 == Compatibility ==
@@ Line 43: / Line 42: @@
 {{Yaku compatibility table|CHK}}
-Excluding kokushi musou, chankan requires at least one sequence in the hand, 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 hand in tenpai with ryanpeikou would require at least one copy of the winning tile, and in order for an opponent to call kan in the first place, you must have no copies of said winning tile. The hand could still win with chankan and [[iipeikou]], though.
+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 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 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 ===
-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, and chankan requires an opponent to call 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 ippatsu and chankan can be scored together.
+=== 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.
-== Special cases ==
+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.
+== Kokushi musou variation ==
 [[Image:Kokushi deny.png|thumb|right|250px|Case where a [[kan|closed kan]] was declared during a [http://tenhou.net/0/?log=2018041311gm-000b-7447-e286a4e6&tw=2&ts=6 kokushi tenpai].]]
+If the rules allow, a special case for [[kokushi musou]] exists. When a kokushi hand is in tenpai, it may win if an opponent calls a closed kan for the tile you are winning for. Thus, ron may be declared, invoking this special rule. This is the only case where a tile may be taken from an closed kan.
-=== Rinshan kaihou ===
+However, this particular rule may be [[Yaku_variations#Kokushi_and_chankan|subject to variation]], which may or may not allow this play to occur.
-Given the procedure for kan, the chankan takes precedence over [[rinshan kaihou]].  Here, the call for a chankan win denies even the drawing of the rinshan tile.  Therefore, even the chance for rinshan kaihou is denied.
-=== Kokushi musou ===
-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.
 ==External links==