Ryanmen
| Kanji | 両面 |
|---|---|
| English | Open wait |
| Fu | 0 fu |
| Tile types waiting | 2 sided wait |
| Tiles available | 8 tiles |
| Pattern example |
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| Tenhou.net example | Using riichi |
Ryanmen 「両面」, often referred as an "open wait", is the most common wait pattern in the game. It involves two consecutively numbered tiles, waiting on either "outside" number. For example, a 3-4 needs either a 2 or a 5 in order to form a sequence of either 2-3-4 or 3-4-5. A ryanmen cannot be formed with terminal tiles. It is, by far, the most efficient wait pattern: it waits for 8 tiles (of two types) while only using 2 tiles.
Pattern
Waiting for: 
or 
Ryanmen always waits for two tiles.
Sanmenchan
Waiting for: , , 
When a ryanmen is adjacent to a complete sequence, forming 5 consecutive number tiles, it forms a sanmenchan - which waits for 3 tiles instead of 2. This is because the hand can be interpreted in one of two ways:
ryanmen + 
sequence; Waiting for: 
,
- sequence + ryanmen; Waiting for: ,
Fu
Due to its relative ease, a ryanmen wait is not awarded any fu.
As it lacks fu, a ryanmen wait is required for pinfu. To score pinfu, you must have a ryanmen (or a complex wait which can be interpreted as ryanmen), as all other waiting patterns end up scoring fu.
Usage
Ryanmen is the most frequently used wait in the game, due to its strength and probability. Approximately 50% of all hands, and 66% of all riichi hands, use a ryanmen wait.
- It is the most powerful of the basic waits. A ryanmen waits for a maximum of 8 tiles of two different types. All other basic wait patterns can wait for a maximum of 4 tiles - ryanmen is twice as big.
- Unlike complex waits, ryanmen only requires two tiles to form, thus making ryanmen much more likely to form than a complex wait.
- Pinfu, a common yaku, requires a ryanmen or ryanmen-derived wait.
Whether a hand is in tenpai or not, ryanmen waits are efficient to use.
Suji
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Suji (i.e. "mahjong intervals") is a defensive concept directly related to ryanmen waits. In essence, when a tile is suji, it would be impossible for an opponent to have a ryanmen wait without being in furiten.
- A ryanmen will always wait on tiles that are three apart, forming the intervals: 1-4-7, 2-5-8, and 3-6-9. For example, a 2-3 ryanmen waits for either a 1 or 4, and is thus part of the 1-4-7 interval.
- Therefore, if an opponent discards a 4, they cannot have a ryanmen wait on a 1 or 7 of the same suit (without being in furiten, which would prevent them from winning off your discarded tile). So after an opponent discards a 4, it is safer to discard a 1 or 7.
- If the opponent discards a 1, then the 4 is not necessarily safe: they could still have a 4-7 ryanmen wait. For 4 to be "full" suji, both 1 and 7 must be discarded.
External links
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