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* [http://tenhou.net/0/?log=2012121311gm-0009-7447-x1c540c2ae0eb&tw=2&ts=4 Chiitoitsu] as [[kazoe]] | * [http://tenhou.net/0/?log=2012121311gm-0009-7447-x1c540c2ae0eb&tw=2&ts=4 Chiitoitsu] as [[kazoe]] | ||
}} | }} | ||
'''Chiitoitsu''' {{kana|七対子}}, also known as '''chiitoi''' or '''niconico''', is one of the standard yaku | '''Chiitoitsu''' {{kana|七対子}}, also known as '''chiitoi''' or '''niconico''', is one of the standard [[yaku]]. It consists of seven pairs. It is one of the two exceptions of the "[[mentsu|four melds and one pair]]" rule for winning hands, the other being [[kokushi musou]]. Because the hand does not use melds, it can only be closed. | ||
Under most rulesets, no two pairs may be identical (certain [[Yaku_variations#Chiitoitsu|house rules]] may allow duplicate pairs, though). | |||
==Tile diagram== | ==Tile diagram== | ||
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==Development== | ==Development== | ||
Given the number of pairs in this hand, it is often tempting to call pon | Tenpai for chiitoitsu always uses the wait of [[tanki]] (pair wait) in order to complete the seventh and last pair for the hand. | ||
Given the number of pairs in this hand, it is often tempting to call pon to turn pairs into triplets. However, [[toitoi]] is generally slower if you do not have any [[ankou]] (triplets) yet. This is especially true if the hand sits at [[iishanten]] for chiitoitsu. | |||
Nevertheless, transitioning to other yaku may be favorable if the hand develops at least one [[ankou]]. In this case, players may find themselves looking to develop a toitoi hand, [[sanankou]], or even [[suuankou]]. Whatever the case may be, this consideration takes some discretion, particularly when taking into account the number of tiles available, current point standing, and/or number of tile draws remaining. | |||
Also, note that the pairs must be distinct; having four of the same tile does not count as two pairs under standard rulesets. Even in rules that do allow four-of-a-kind to count as two pairs, a call for "[[kan]]" would not count, as a kan is treated as a triplet. | |||
===Hand interpretation=== | |||
Unlike most mahjong hands, chiitoitsu is an exception to the "four [[Mentsu|groups]] and a pair" pattern. Instead, tiles are groups into pairs or toitsu. As such, the tile groupings cannot be interpreted other ways. For this reason, chiitoitsu is also granted a unique fu count of 25, which remains static. | |||
===Shanten=== | ===Shanten=== | ||
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| 1 || 5 || {{#mjt:11m4477p8899s136z}} | | 1 || 5 || {{#mjt:11m4477p8899s136z}} | ||
|- | |- | ||
| 2 || 4 || {{#mjt: | | 2 || 4 || {{#mjt:11m2447p8899s136z}} || A hand with four pairs may consider for chiitoitsu. Only one more pair is needed to get to 1-shanten. | ||
|- | |- | ||
| 3 || 3 || {{#mjt: | | 3 || 3 || {{#mjt:11m2447p6899s136z}} || A hand with three pairs is very inefficient. | ||
|- | |- | ||
| 4 || 2 || | | 4 || 2 || {{#mjt:16m2447p6899s136z}} ||rowspan=2|Attempting chiitoitsu with this start is very unreasonable. If anything a hand of this composition is better off utilizing other yaku. | ||
|- | |- | ||
| 5 || 1 || | | 5 || 1 || {{#mjt:16m2457p6899s136z}} | ||
|} | |} | ||
== | == Compatibility == | ||
{{main|Yaku compatibility}} | |||
{{main|Yaku | |||
{{Yaku compatibility table|CHI}} | {{Yaku compatibility table|CHI}} | ||
The composition of this yaku makes it very restrictive regarding its combination with other yaku. | The composition of this yaku makes it very restrictive regarding its combination with other yaku. Chiitoitsu cannot be combined with any yaku dependent on [[mentsu|tile groups of three]], as this yaku consists of only pairs. Chiitoitsu combined with [[chanta]] gives [[honroutou]], and it cannot be combined with [[junchan]] as there are only six different terminals, but chiitoitsu requires seven distinct pairs. | ||
This yaku forbids kan, so [[rinshan]] is incompatible. [[Chankan]] is also incompatible. A hand in tenpai for chiitoisu always has a copy of the winning tile, thus making it impossible for other players to make the added kan call required for chankan. | |||
=== With iipeikou or ryanpeikou === | === With iipeikou or ryanpeikou === | ||
A chiitoitsu hand may collect sequential series of paired tiles | A chiitoitsu hand may collect sequential series of paired tiles, which may look like [[iipeikou]] or even [[ryanpeikou]]. Both yaku are incompatible with chiitoisu, as once again, all tiles are considered to be in pairs, not [[mentsu|sequences]]. | ||
==Value== | ==Value== | ||
{{main|Scoring table}} | {{main|Scoring table}} | ||
As a special exception to | As a special exception to scoring, this hand is always given 25 [[fu]]. No other fu are awarded: not for yakuhai pairs, [[tanki]] waits, or closed ron. It is not rounded up to 30 fu. This produces a distinct set of scoring values: | ||
{| class="wikitable" width=70% | {| class="wikitable" width=70% | ||
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|} | |} | ||
High scoring chiitoitsu hands are possible without dora. | A 2 han chiitoitsu tsumo is not possible, as chiitoitsu is always closed, so it also scores [[mentsumo]]. Like all hands, once you reach 5 han or more, fu is no longer relevant for scoring. | ||
Note that, if the hand is below [[mangan]], chiitoitsu can be thought of as a 1 han 50 fu hand. | |||
*2 han 25 fu = 1 han 50 fu | |||
*3 han 25 fu = 2 han 50 fu | |||
*4 han 25 fu = 3 han 50 fu | |||
High scoring chiitoitsu hands are possible even without dora. The highest possible hand is [[riichi]], [[ippatsu]], [[menzenchin tsumohou|tsumo]], [[haitei raoyue and houtei raoyui|haitei]] and [[chinitsu]]. With the 2 han for chiitoitsu, the combination brings the hand to a whopping 12 han. Note that [[tanyao]] cannot be added, as the hand 22334455667788 can be scored as [[ryanpeikou]] for an additional 1 han. In some [[rule variations#Daisharin|rule variations]], this hand is an [[optional yaku|optional yakuman]], known as "daisharin", "daichikurin", or "daisuurin", depending on the suit. | |||
=== With dora === | === With dora === | ||
{{main|Dora}} | {{main|Dora}} | ||
All tiles in this yaku must be in pairs. Therefore the dora tiles also tend to occur in pairs. The [[Akadora|red dora]], if used, are exceptions, since they can be paired with non-red versions of the tile. | |||
==External links== | ==External links== |
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