Monday 13 February 2012

Defence theory(16): Tricks to defending

Source: http://blog.jpmahjong.net/read.php/567.htm

In the previous articles, we discussed betaori techniques when someone has declared riichi or when defending. However, to truly defend is not just about defending when someone attacks. As the discards increases, the chances of the other players reaching tenpai increases. If you put in a little effort in some details, you can avoid dealing in.

A few commonly seen techniques are shown below.

Discard the good tile first\Keep the safe tile
For example, like the hand below.


A hand in iishanten, and the 4 sou is an useless tile.
Let's assume that you next draw a dead tile, nan. If the situation doesn't look dangerous, you'd normally discard 4 sou first. This is what it means by discarding the good tile first.


The theory behind discarding the good tile first, is that 4 sou has a higher chance of becoming a dangerous tile than nan in the future. Since 4 sou is useless to us, you should discard it before someone reaches tenpai, in order to get rid of the risky tile that would be in your hand when you reach tenpai.

The tactic about keeping the safe tile should not be abused.


If we change 4 sou to 7 sou, the situation is very different. If you draw nan this time, you should definitely discard it.
Previously when I was still playing in high level games in 東風莊, I would discard 7 sou and keep nan with these type of hands. But in modern day mahjong theories, this is a conservative method. In the image above, there are 20 tiles that can be added into the hand. But if we were to discard 7 sou for a safe tile, the number of effective tiles would be 16. This a significant 20% loss when compared to the former.

The first condition when keeping the safe tile is to not sacrifice tile efficiency. With the hands below, a safe tile would be discarded if drawn.


At the beginning of the hand, 4 sou should not be discarded, it has a chance of becoming a ryanmen.


 As 2356 pin has effective tiles repeating, it cannot be considered as a good shape. At the beginning of the hand, 7 sou should be kept, but can be tricky after the middle discard rounds.

Going into betaori early
Mahjong is played by four players, and each player has a 25% chance of winning. Among them are hands that have very little chance of winning, for example:


This is a sanshanten hand with many bad shapes, and there is no way to increase the speed via calling tiles. If your hand remains this way even after the 5th or 6th, unless you make godly draws, your chances of winning is close to zero. Since you can't win, you should try to minimize your losses. Hence going into betaori is the best choice here.

Discard tiles that have been discarded by other players(kamicha would be the best) in the same discard round, and keep the tiles(like word tiles) that have a high degree of safety. If someone declares riichi later, you can remain in a safe state and reduce dealing in to the minimum. This method also protects you from dealing in to the damaten of other players.

Normally, a sanshanten hand in the 6th discard round and a ryanshanten hand in the 12th discard round has zero chance of winning. With this sort of tiles, you can either call tiles and try to win or go into betaori. Just like in poker, it's not possible to have a good hand every single round. Attempting to win when you have a bad hand will only cause you to incur more losses.

The two theories originate from the principle below.
Discard the dangerous tile before someone reaches tenpai.
Discard safe tiles sequentially after someone reaches tenpai .

This is the true essence of reducing the chances of dealing in.

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