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This article describes basic technique on Betaori: discarding safe tile without intention to win the round.
I was 2nd at East 3, but the situation was almost flat. I decided to fold against the Riichi of the player on the right, but I don’t have obvious safety tile. What to discard ?
I dropped 8m. There is one simple principle on Betaori, “when we don’t have 100% safety tile, we should drop pairs”.
In this case deal in rate of 9p or 2p may be lower than 8m, but if this 8m doesn’t hit, you can buy 100% safety on next turn, and this is very important in the situation like this.
The following are not exact calculations.. But if deal in rate of 8m is 6%, (15 Suji is alive, and not bad estimate I assume), that of 9p is 4%, that of 2p is 5%, when you drop 8m pair, you will have 6% chance to deal in. If you discard 9p and then 2p, you will have 100%-(100%-4%)x(100%-5%)=8.8% chance to deal in, which is higher than 6%.
I also had 4s pair, but I don’t recommend to drop 4-6 pair, because deal in rate of those tiles are high: almost double as 2378 and 19 is lower.
In this situation, eventually 2p hit to the Riichi, and I succeeded to keep my position.
Lastly, I want to quote one interesting comment of Hirasawa, Japanese Pro, and famous Youtuber. “In tile efficiency, we have just 2-3 choices, but in Betaori we will have much wider choices. So it is easier to differentiate yourself by the skill of Betaori”.
Hope this article will be of some help to you !