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Revision as of 20:37, 17 March 2024

12 bytes added ,  17 March
tenhou.net and derived rulesets allow kan so long as it does not change waits. since i'd imagine most readers would play in online clients, it's important to note
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m (→‎Suukaikan: mention that the hypothetical 5th kan is immune to chankan)
(tenhou.net and derived rulesets allow kan so long as it does not change waits. since i'd imagine most readers would play in online clients, it's important to note)
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=== Kandora timing ===
=== Kandora timing ===
The call for kan reveals additional dora, in the form of [[dora|kandora]].  The timing of this reveal is variable, depending on [[Dora variations|the rule set and/or game platform]].  The simplest rule invokes an immediate reveal upon the declaration; and so, this rule would immediately place the kan reveal after step 1.  Others distinguish the timing between open and closed kans.  Here, closed kans would be granted an immediate reveal; however, open kans would produce another kandora indicator after the discard, upon conclusion of the kan process at step 8.  Regarding the timing of the kandora, players will need to consult organizational, tournament, and/or local rules.
The call for kan reveals additional dora in the form of [[dora|kandora]].  The timing of this reveal is variable, depending on [[Dora variations|the rule set and/or game platform]].  The simplest rule invokes an immediate reveal upon the declaration; and so, this rule would immediately place the kan reveal after step 1.  Others distinguish the timing between open and closed kans.  Here, closed kans would be granted an immediate reveal; however, open kans would produce another kandora indicator after the discard, upon conclusion of the kan process at step 8.  Regarding the timing of the kandora, players will need to consult organizational, tournament, and/or local rules.


==Kan types==
==Kan types==
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{{main|Riichi}}
{{main|Riichi}}


Kan calls after riichi is possible and may be allowed or disallowed depending on the hand's composition.  Under all of these cases, the call for a closed kan is used.  The other two types of kan calls cannot occur, as riichi requires closed hand.
A player may be allowed to call a closed kan during riichi, depending on the hand's composition.


When a riichi declarer holds three identical tiles and draws the fourth after the riichi announcement, the player may form an [[Kan|ankan]] from these tiles instead of discarding the fourth. The hand composition and the possible winning tiles may not change: it is not allowed to declare kan if, for some possible winning tile, any of the three identical tiles may be interpreted as part of a [[shuntsu|sequence]] or part of the pair.
Under most professional rulesets, a player is not allowed to call kan if it would change the hand's possible winning tiles, or if it would change any possible interpretation of the hand. If, for any winning tile, any of the three identical tiles can be interpreted as part of a [[shuntsu|sequence]] or part of the pair, the kan is not allowed.
 
Under some rulesets, such as in [[tenhou.net]] and [[Mahjong Soul]], an alternative is used: so long as a kan does not change the hand's possible winning tiles, the kan is allowed. (I.e., even if a kan would change a possible interpretation of the hand, it is allowed.)


If a player does declare a kan illegally during riichi, and they call [[ron]] or the game goes to an [[ryuukyoku|exhaustive draw]], then they will be penalized with a [[chombo]] penalty for breaking the rule. If a player is not required to reveal their hand, or if another player wins, they will normally not be penalized.
If a player does declare a kan illegally during riichi, and they call [[ron]] or the game goes to an [[ryuukyoku|exhaustive draw]], then they will be penalized with a [[chombo]] penalty for breaking the rule. If a player is not required to reveal their hand, or if another player wins, they will normally not be penalized.


Of course, a player may outright decline the call for kan and discard the drawn tile.  After all, the play invokes a risk pertaining to the kandora. During a riichi call, the player is defenseless against the benefactors of the new dora.
Of course, even if a kan is allowed, players may choose to decline a kan call. While a player can benefit from kan dora (and kan uradora), so will their opponents.


'''Example 1:'''
'''Example 1:'''
:{{#mjt:3444m778899s333z}} Illegal kan: {{#mjt:4m}} Legal kan: {{#mjt:3z}}.
:{{#mjt:3444m778899s333z}} Illegal kan: {{#mjt:4m}} Legal kan: {{#mjt:3z}}.


It is not allowed to kan the fours. The manzu tiles may either be interpreted as a 3-4 [[Ryanmen|ryanmen]] wait and a 4-4 pair, or as a 4-man ankou with a 3-man [[tanki]] wait. A kan call would alter the wait just for a 3-man tanki. For a legal kan declaration, the three identical tiles would have to be an ankou in any interpretation. Had the player drawn a west wind, he would have been allowed to kan it.
It is not allowed to kan the fours. The manzu tiles may either be interpreted as a 3-4 [[Ryanmen|ryanmen]] wait and a 4-4 pair, or as a 4-man ankou with a 3-man [[tanki]] wait. Overall, the hand waits for 2-5-3 man. A kan call would change the wait to just the 3-man tanki, and is thus forbidden. It is allowed to kan the west winds, since they would be considered an ankou no matter which tile is won.


'''Example 2:'''
'''Example 2:'''
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'''Example 3:'''
'''Example 3:'''
:{{#mjt:3335666p111456s}} Illegal kan: {{#mjt:36p}}
:{{#mjt:3335666p111456s}} Potentially illegal kan: {{#mjt:3p}} Illegal kan: {{#mjt:6p}}  
 
Here, the waits are 457p. A kan on 6p would remove the 7p wait, so it is obviously not permitted.


Here, the waits are 457p. A kan on 6p would remove the 7p wait, so it is obviously not permitted. A kan on the 3p would not change the waits, however, if the hand was won with 4p, the hand could be interpreted as:
A kan on the 3p would not change the waits. However, if the hand was won with 4p, the hand could be interpreted as:


:{{#mjt:33p}} {{#mjt:345p}} {{#mjt:666p}} {{#mjt:111s}} {{#mjt:456s}}
:{{#mjt:33p}} {{#mjt:345p}} {{#mjt:666p}} {{#mjt:111s}} {{#mjt:456s}}


In this case, the 3p does not form a [[koutsu|triplet]], but rather a pair and a part of a sequence. A kan on the 3p would remove this potential interpretation of the hand, and is therefore forbidden.
In this case, the 3p does not form a [[koutsu|triplet]], but rather a pair and a part of a sequence. A kan on the 3p would remove this potential interpretation of the hand, and therefore may be forbidden (depending on ruleset).


'''Example 4:'''
'''Example 4:'''
:{{#mjt:222333444p23m11z}} Illegal kan: {{#mjt:2p}} {{#mjt:3p}} or {{#mjt:4p}}
:{{#mjt:222333444p23m11z}} Potentially illegal kan: {{#mjt:2p}} {{#mjt:3p}} or {{#mjt:4p}}


In this example, a kan declaration does not change the wait, but it does change the possible interpretations of the hand. The pinzu section can be interpreted either as three consecutive triplets or three identical sequences :  
In this example, a kan declaration does not change the wait, but it does change the possible interpretations of the hand. The pinzu section can be interpreted either as three consecutive triplets or three identical sequences :  
:{{#mjt:222p}} {{#mjt:333p}} {{#mjt:444p}} or {{#mjt:234p}} {{#mjt:234p}} {{#mjt:234p}}
:{{#mjt:222p}} {{#mjt:333p}} {{#mjt:444p}} or {{#mjt:234p}} {{#mjt:234p}} {{#mjt:234p}}
In this case, a kan call on any of the pinzus would leave only the three triplets interpretation possible. Thus, any of these kan is deemed illegal after riichi, even though it doesn't change the waits.
In this case, a kan call on any of the pinzus would leave only the three triplets interpretation possible. Thus, any of these kan would be deemed illegal after riichi (depending on ruleset).


===Last tile===
===Last tile===
Hordes
692

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