The aim of this article is to develop your perception towards betaori, while also introducing some high level techniques.
[First image in http://blog.jpmahjong.net/read.php/547.htm]
It's south round first hand in the above picture, kamicha declares riich on the 8th discard, what should Ton do?
First you should find out, is this a situation to go into betaori for?
Ton gained a considerable advantage from the east round, the important thing to do now is to reduce the amount of points loss in the south round. Even though the pinfu dora 2 is a good hand, but it's only ryanshanten, in a situation where you're leading, I believe going into betaori is a correct choice.
Once you know you need to go into betaori, the next step would be finding the safe tiles. The genbutsu of kamicha are currently 4 pin and chun. While 1 wan is the safest tile outside of genbutsu. (1 wan is a no chance tile, don't forget the 2 wan that was pon.) I'll take the opportunity to mention, a lot of beginners believe that just because kamicha discard 1 and 3 sou, 2 sou would be a safe tile. This is a misconception.
Then, the genbutsu of 4 pin and chun, which should be discarded first? I will first discard 4 pin, there are two reasons for this.
1) Currently, 4 pin is an absolutely safe tile. (Kamicha has discarded 4 pin before, therefore he/she cannot win on the 4 pin.)
2) Another reason for discarding 4 pin, is expecting shimocha to call on it and continue to attack. From this current situation, kamicha who is in third is in riichi, shimocha who is in fourth won't go into betaori easily. Deliberately letting shimocha call your tile, is to cause a situation where both players attack each other, increasing the chances of dealing in for both players. In other words, decreasing your chances of dealing in. This is a practical high level technique.
A lot of readers may feel that discarding chun and maintaining the taatsu is still commendable. However everyone has to understand this, to reach tenpai with this hand, you need to gamble on discarding 2 sou and 9 sou, both of which are not suji-pai. With this situation in points, this is too much of a gamble.
Betaori, is not just about finding a few genbutsu and discarding them. One of the important points of an excellent betaori technique, is to take stock of the situation, list out an accurate discard order, and genuinely decreasing your chances of dealing in to the lowest.
I hope that everyone can continue to improve their betaori.
(To be continued.)