## Tenpai

### Keiten & Karaten

According to [ja.wiki][karaten-wiki]:

> 形式聴牌（けいしきてんぱい）とは、(ツモ・ロンによらず) 役のないテンパイのこと。門前を崩したためリーチがかけられず、三色や対々などの手役もないテンパイ形のことである。しばしば形聴 (けいてん) と略される。

> 空聴（カラテン）とは、形としては聴牌しているものの、捨牌や副露、ドラ表示牌などで和了牌が全て見えており、和了の望みがない状態のことである。純カラ聴牌、純カラ (じゅんカラ) とも呼ばれる (純カラは「純粋に空っぽ」の略) 。以下に挙げるように複数の場合が考えられる。ノーテン罰符のやり取りにおいて聴牌と扱われるか否かは取り決めによる。

According to [arcturus.su][karaten-arcturus]:

> **Karaten** 「カラテン」, or empty tenpai, is a state where a tenpai hand does not have the ability to win. This is due to unavailability of all instances of winning tiles. The "visible tiles" may either be discarded, used as a dora indicator, or already exist in one's hand. Furthermore, they may be held in other player's hands or even reside within the dead wall. Though, the latter case is beyond a player's visibility.

> **Keishiki tenpai** 「形式聴牌」 is a special case the hand waits for a "5th tile". This case may be karaten with particular waiting patterns, such as penchan or kanchan. Under some rule variations, a keishiki hand may be considered as noten under the following circumstances:
> *   All hand-completing tiles are already used within the player's own hand. If a player has a 1-2 penchan and a previously declared kan of 3-3-3-3 in the same suit, no more threes are available as winning tiles.
> *   All hand-completing tiles are visible among declared kans, open melds, discards, and dora indicators. Only some rules have such a large scope for karaten.

Summarized:

Tenpai is sometimes valid (i.e. you can riichi and there is no penalty for no-ten) even when you cannot win:

*   Lack of yaku: **YES**
*   All waits visible: depends, see table below

Zone | Valid?
-----|--------
Kawa {discards} | almost always yes
Fuuro {melds} (others) | almost always yes
Fuuro {melds} (yours) | usually yes
Dora hyoujihai {indicator} | usually yes
Your own juntehai {concealed part of hand} | **NO**


[karaten-wiki]: https://ja.wikipedia.org/wiki/%E8%81%B4%E7%89%8C#.E3.83.8E.E3.83.BC.E3.83.86.E3.83.B3.E7.BD.B0.E7.AC.A6.E3.81.AB.E9.96.A2.E4.BF.82.E3.81.99.E3.82.8B.E8.81.B4.E7.89.8C

[karaten-arcturus]: http://arcturus.su/wiki/Tenpai


## Ron

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*   Atamahane
*   Double
*   Triple

[ron-wiki]: https://ja.wikipedia.org/wiki/%E5%92%8C%E4%BA%86#.E9.A0.AD.E3.83.8F.E3.83.8D.E3.83.BB.E3.83.80.E3.83.96.E3.83.AD.E3.83.B3.E3.83.BB.E4.B8.89.E5.AE.B6.E5.92.8C