Machi

Machi 「待ち」 is the Japanese term for "wait patterns". Given any mahjong hand at any instance, players are waiting for specific tiles either to develop their hands or complete it. Wait patterns arise during hand development, when mahjong tiles in possession in the hand are in need of other tiles in order to complete mentsu (tile groups) or the entire hand. Wait patterns during tenpai are of particular interest, as they indicate winning tiles. Players in tenpai must know their waiting tiles, or else end up missing a winning tile.

Five patterns here are classed as "basic wait patterns". These five patterns occur frequently; and they are not dependent on other patterns for formation. A combination of any of these five, including themselves, can form more complicated patterns.

Overview

Many different patterns arise during the course of hand development. Once a hand reaches tenpai, being able to interpret the hand's available winning tiles is a vital skill. If a player does not correctly read their winning tiles, they may miss a valid win, or they may commit a chombo with an illegal win call: either by calling a win on a tile that does not complete the hand, or calling ron while furiten due to a tile that they did not realize would complete the hand.

The most commonly occurring wait patterns have been given names, to make them more easily recognizable. More complex waits can arise involving a large number of potential configurations of the hand. This is especially true of hands with a large number of tiles in the same suit, most notably those aiming for chinitsu. Knowing the basic wait patterns also helps to combine them to interpret complex hands, which may have as many as 8 weights (not counting the special cases of chuuren poutou and kokushi musou, which are easily recognizable).

Wait counts

Main article: Ukeire

The waiting patterns can be analyzed using two numbers: n-sided waits and n-tiles available. This counts the number of tile types and the number of tiles themselves.

Patterns waiting for n-sided look for the number of tile types count as winning tiles. The largest number involves kokushi musou with a 13-sided wait pattern. The smallest number is 1.

As for counting the number of tiles available, this accounts every tile type having 4 copies each. Maximum possible counts exclude tiles required in the hand. Any tiles in other players' hands, the dead wall, or discarded tiles are not factored to this count. Of course, during the course of a hand, players must take into account the number of available tiles along with the maximum count.

Hand development

Main article: Tile efficiency

During hand development, it is important to understand the hand's machi for two reasons. The first is that, when trying to bring a hand to tenpai, a player will want to maximize the number of available tiles to bring them closer. Doing this requires interpreting the patterns of potential groups in a similar manner to finding tile waits in a tenpai hand. The second is that furiten is best avoided, and so a player should avoid making discards that would leave them furiten once they reach tenpai. This can be a particular challenge when developing single-suited hands that may have a large number of different waits.

Basic wait patterns

These five are essentially the basic wait patterns. Upon tenpai, they only look to complete either the last tile group or the pair.

Name	Kanji/Kana	Header text
Ryanmen	両面	Waiting for:
Penchan	辺張	Waiting for:
Shanpon	双ポン	Waiting for:
Kanchan	嵌張	Waiting for:
Tanki	単騎	Waiting for:

Named combinations

The basic patterns can be combined for more complex patterns; and the wait patterns listed here have taken on names.

Name	Kanji/Kana	Header text
Nobetan	延べ単 ノベタン	Waiting for:
Standard Sanmenchan	狭義の三面張	Waiting for:
Sanmentan	三面単	Waiting for:
Entotsu	煙突系 エントツ	Waiting for:
Aryanmen	亜両面	Waiting for:
Ryantan	両単	Waiting for:
Pentan	辺単	Waiting for:
Kantan	嵌単	Waiting for:
Kantankan	嵌単嵌	Waiting for:
Tatsumaki	竜巻	Waiting for:
Happoubijin	八方美人	Waiting for:

Double yakuman patterns

These two unique patterns are linked to specific yakuman. Under all possible tile waits with these patterns, yakuman is ensured; under some scoring rules, winning a hand with these patterns is awarded double yakuman. There are no other wait patterns with more than 8 winning tiles (although it is possible for an 8-sided wait to include four of the same tile in such a way that a hypothetical fifth copy of the same tile would complete the hand).

Chuuren poutou kyuumen machi

Main article: Chuuren poutou

Waiting for:

Kokushi musou 13 machi

Main article: Kokushi musou

Waiting for:

Complex patterns

Main article: Complex waits

These combinations involve patterns that do not have specific names. Instead, they use combined forms of the other patterns. Furthermore, they mostly consist of consecutive, or closely consecutive, numbered tiles. Recognition of these patterns can produce some significantly powerful waits, which may be immune to suji and have large numbers of waiting tiles.

Related terminology

Karaten

Main article: Karaten

Karaten 「カラテン」, or empty tenpai, is the case where there are no tiles left to win with, due to all potential winning tiles already having been used in the player's hand, a discard pool, a called group, or visible as dora indicators. In some rulesets, a hand in this state is considered noten at an exhaustive draw.

Takame and yasume

Main article: Takame and yasume

Takame is a potential winning tile which is worth more points than another, called yasume.

External links

• 聴牌

Machi in Japanese Wikipedia

• ReachMahjong wait guide

Forum list of various patterns

• Tenhou wait calculator

Wait survey quiz in Tenhou.net