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name the header "discard furiten" instead of "common case", since discard furiten is the class of furiten being talked about
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(name the header "discard furiten" instead of "common case", since discard furiten is the class of furiten being talked about)
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[[Image:Furiten.png|right|thumb|250px|Baiman tenpai, in furiten due to 9-sou in discard.  Ron cannot be called here.]]
[[Image:Furiten.png|right|thumb|250px|[http://tenhou.net/0/?log=2012110112gm-0009-7447-14ec5c8d&tw=0&ts=4 Baiman tenpai], in furiten due to 9-sou in discard.  Ron cannot be called here.]]
'''Furiten''' {{kana|振聴}}, meaning '''sacred discard''', is a particular rule associated with the tile discards. Unlike many other mahjong variations, the [[discard pile]] for Japanese mahjong is specifically arranged in front of players.  Likewise, [[naki|tile calls]] have specific arrangements to point the source of these discarded tiles. The main purpose is the enforcement of the '''furiten rule'''. Basically, the player in [[Tenpai|tenpai]] is furiten if winning tiles are present in one's own discard pile or other player's discard pile, barring certain conditions.  Players in furiten may still win by tsumo, but not by ron.
'''Furiten''' {{kana|振聴}} is a restriction applied to [[tenpai]] hands. While in furiten, the player loses the ability to declare a win on any player's [[ron|discard]] (ron). The most common form of furiten is with discards: if any tile the hand could have won off is in a player's discard pile, it is furiten. This includes any tiles [[naki|called by opponents]].  Other cases involving riichi and temporary furiten are also applicable.  Regardless, the hand can still win by [[tsumo|self-draw]] (tsumo) given valid [[yaku]].


== The rule ==
This rule is often used for [[defense]] purposes to determine [[Genbutsu|safe tiles]]. Tiles with the furiten rule can be inferred via [[suji]], though this may not be guaranteed.
Furiten imposes the following conditions:
* '''Players in furiten may not win by ron''', even if they have a yaku.
* Declaring ron while in furiten is penalized with a [[Chombo|chombo payment]].
* Players in furiten may still win by tsumo.


== Causes ==
== Rule statement ==
A hand in tenpai is in furiten in any of the following scenarios:


With regards to furiten, all cases of furiten involves the discard pile. When a player has called a win, particularly via the call for ron, the discard pile is checked for furiten along with a few other rules. In event when furiten is determined among the discards after the the call for ron, then chombo is enforced. For games played via the computer, players are denied the ability to declare "ron" in the first place.
* At least one winning tile is in one's own discard pile. This applies even if the hand could not actually win off that tile (due to lacking yaku).
* The hand is declared [[riichi]] and the (first) winning tile is not claimed. This is known as permanent furiten.
* The hand is not declared riichi, another player discards a tile, and the winning tile is not claimed, even if the hand could not actually win. Then the hand is in temporary furiten and cannot ron until the player has discarded.


=== Discard-based furiten ===
While in furiten, the hand is unable to call ron upon a discard. However, it is still winnable via self-draw, assuming the hand has valid yaku. Note: when any winning tile triggers furiten, the ''entire'' hand is furiten.
 
=== Discard furiten ===


{{Discard pile
{{Discard pile
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}}
}}


A player is furiten if a winning tile is present in his own's [[discard pile]]. It does not matter whether this tile would have provided a yaku or not. Tiles turned sideways within open melds are considered part of their discarder's discard pile.
The most common case of furiten involves a player's own discard. If a winning tile is in a player's discard, then the hand is in furiten.


As long as the player has not declared [[Riichi|riichi]], furiten can be avoided by altering the hand and changing [[Machi|tile waits]].
All of a player's discards can be checked at any time during play, by looking at their discard pools and the rotated tiles in other players' tile calls. This leads to the most basic strategy to avoid dealing into a player's hand: tiles they have already discarded are guaranteed to be safe against a ron call from that player.


'''Example tenpai hand'''
During hand development, it is important to bear furiten in mind. Most of the time, if a hand gets to tenpai and is furiten at that point, it indicates that the hand was inefficiently developed. This is not always the case, as sometimes a player makes a tactically correct decision and finds themselves in furiten anyway.
:{{#mjt:77m 34567p 678s 777z}}, waiting on {{#mjt:2p}}, {{#mjt:5p}}, or {{#mjt:8p}}


This hand waits on three different tiles. If the player has a 2-pin the discard pile, then the hand is in furiten and may not win by ron on any tile. Even if a 5-pin or 8-pin gets discarded by an opponent, ron may not be called in this instance.
The most common reason for furiten, however, is when a player is already tenpai with an open hand, and does not have a guaranteed yaku. While they may have a winning tile that provides them with a yaku, if they draw another tile which completes the hand without a yaku, then they will be forced into furiten on the next discard. This most commonly occurs when the hand has:
*A [[shanpon]] wait, with one tile completing a [[yakuhai]] triplet, and the other having no yaku.
*A [[ryanmen]] wait on 14 or 69 on a hand that would otherwise complete [[tanyao]].
These type of cases are known as [[atozuke]].


=== Permanent furiten during riichi ===
Finally, a player considering a [[daburu riichi|double riichi]] should carefully inspect their hand before discarding; if they had a complete hand to begin with, then being in furiten will add insult to the injury of having [[http://osamuko.com/delicious-riichi-button-must-click-it/ passed]] on a [[tenhou and chiihou|tenhou or chiihou tsumo]].
{{main|Riichi}}


A riichi declarer may ignore a winning tile and not call ron. The ignored tile may have been a discarded tile or a [[Chankan|tile used to extend a minkou to a shominkan]].  After ignoring a winning tile, the riichi declarer is permanently furiten for the rest of the hand.  Therefore, it is advised for any player declaring riichi to call ron, at the first instance of a winning tile.  Otherwise, a win via [[mentsumo|tsumo]] becomes the only option.
'''Example tenpai hand'''
:{{machi
|pattern      = 77m34567p678s777z
|tilewaits    = 258p
}}


The furiten rule emphasizes that all tiles discarded by any player after the riichi declaration are deemed [[genbutsu|safe tiles]], in addition to the player's own discards. Riichi declarers may not decline a ron against one player and expect to declare ron against another. Even if a winning tile different from the ignored one appears, the player may not call ron. This rule requires knowledge of all own [[machi|possible waits]].
This hand waits on three different tiles. If the player has a 2-pin in their discard pile, then the hand is in furiten and may not win by ron on any tile. Even if a 5-pin or 8-pin gets discarded by an opponent, ron may not be called.


=== Temporary furiten ===
=== Temporary furiten ===
[[Image:TempFuriten.png|thumb|right|250px|Ron declined, so [http://tenhou.net/0/?log=2014022617gm-0089-0000-ee8c6631&tw=2&ts=11 temporary furiten invoked] until the next own's tile draw.]]
[[Image:TempFuriten.png|thumb|right|250px|Ron declined, so [http://tenhou.net/0/?log=2014022617gm-0089-0000-ee8c6631&tw=2&ts=11 temporary furiten invoked] until the next own's tile draw.]]
A tenpai player who has not declared riichi may also ignore a winning tile. In some plays, this may be a valid option in order to achieve a higher scoring hand or to target a specific player.  By declining a call for ron, the player then becomes temporarily furiten until the next own discard. Some rules additionally cancel temporary furiten on any [[naki|tile call]] by any player.
Any player in tenpai has the option to ignore a winning tile. By declining a call for ron, the player then becomes temporarily furiten until their next discard. This is called '''temporary furiten''', as it expires shortly after it occurs. This applies to a discarded tile, as well as tiles used to create a [[shouminkan]]. [[Ankan]] are exempt: the only hand that can ron of an ankan is a single-sided [[kokushi musou]], and if ron happens to be skipped, the hand becomes impossible.


The furiten rule does not consider [[yaku]]. Sometimes, a hand can be completed with several tiles, but only some of them provide a yaku, others would produce a yakuless hand. If a yakuless tile appears, it must be ignored, because a winning hand must contain a yaku. The player must remain temporarily furiten.
The primary purpose of the rule is to prevent a player from targeting a later player in the turn order. Once a player sees a tile discarded, they know that they can follow with the same tile and it will be safe for that turn.


This rule makes it harder to target a specific player with ron, or to ignore a winning tile of lesser value and hope for a tile giving more yaku. Sometimes, a player simply needs a specific win condition in order to attain a certain result, like [[Gyakuten|passing another player]]. Win conditions that do not meet certain requirements may end up being ignored.
While this is often a mistake to enter temporary furiten, done by a player who does not know their waits correctly or is not paying attention, it may be done deliberately in order to achieve a higher scoring hand or to target a specific player. This becomes much more common in [[orasu]], where a player may gain little benefit from winning a hand that does not [[gyakuten|let them pass another player]]. Temporary furiten can also be entered by a player who does not have a guaranteed yaku, as described above. This is much less devastating than drawing the [[yasume]] tile, however, because it is only temporary.
 
Uncommonly, some rulesets [[Rule variations#Furiten|vary the rules]] by allowing a tile call made by another player to cancel temporary furiten. This variation is considered by many to be a poor one.
 
=== Permanent furiten during riichi ===
[[Image:Furiten riichi.png|250px|thumb|right|[http://tenhou.net/0/?log=2015082022gm-0089-0000-a1177c83&tw=1&ts=11 Furiten riichi] applied upon declaration and discard declining a winning hand.]]
{{main|Riichi}}
 
When a player has declared riichi, the state of temporary furiten does not expire. Per the rule of riichi, a player cannot change wait. Therefore, the hand can no longer be adjusted to escape furiten.  The only one opportunity to call ron comes from the first instance of a winning discarded tile.  If the call to win is declined, then the only option to win the hand comes via tsumo. This rule is a critical part of defense against riichi, as it means that any tiles discarded since the declaration is safe to the riichi called player.
 
A player in riichi never has to worry about [[yasume]] putting them in furiten unless they are playing with [[ryanhan shibari]]. When ryanhan shibari, a riichi without a guaranteed second yaku may be quite dangerous due to furiten.


== Strategy ==
== Strategy ==
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The furiten rule may be applied for defensive play, which focuses on discarding [[safe tiles]]. By discarding tiles that are also visible in an opponent's discard pile, a player can avoid a ron call by that opponent.  Likewise, usage of [[suji]] and [[kabe]] may also help players deduce safe tiles, based on opponent discard.  This is applied when a player does not have any matching tiles in the hand with opponent discard; or a player may rather keep certain tiles, for the sake of developing the hand without [[betaori|tearing it apart]].
The furiten rule may be applied for defensive play, which focuses on discarding [[safe tiles]]. By discarding tiles that are also visible in an opponent's discard pile, a player can avoid a ron call by that opponent.  Likewise, usage of [[suji]] and [[kabe]] may also help players deduce safe tiles, based on opponent discard.  This is applied when a player does not have any matching tiles in the hand with opponent discard; or a player may rather keep certain tiles, for the sake of developing the hand without [[betaori|tearing it apart]].


===Dealing with furiten===
===Working with furiten===
 
Sometimes, it may be necessary to deliberately place the hand in furiten.  Often, this is the result of developing the hand and defending simultaneously.  To escape the bind applied by furiten, then the hand's [[machi|tile wait(s)]] must simply change by adjusting and changing the tiles in the hand with subsequent tile draws.  Of course, a player may place greater expectation on tsumo to win rather than ron.


Sometimes, it may be necessary to deliberately place the hand in furiten.  Often, this is the result of developing the hand and defending simultaneously.  To escape the bind applied by furiten, then the hand's [[wait|machi]] must simply change.
On rare occasions, a player may hold a tenpai hand with [[damaten]].  The hand may invoke [[riichi]], but the player had chosen not to for some reason.  Eventually, a winning tile may arrive; and instead of declaring a win, the player opts to call riichi.  That instantly puts the hand in furiten opting to win by tsumo later.


=== Furiten tsumo ===
=== Furiten tsumo ===


Hands in furiten can still win.  However, furiten imposes a limit of tsumo only.  For open hands, the hand then requires a valid yaku.  For closed hands, then [[mentsumo]] will be acceptable or added.
Hands in furiten can still win, as furiten imposes a limit of tsumo only.  For open hands, the hand requires a valid yaku.  For closed hands, [[mentsumo]] will be acceptable or added.


== External links ==
== External links ==
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