Mahjong Strategy: Push or Fold 4 part2 / Maximizing Game EV

This article is on Push or Fold judgement considering game EV, not round EV. Please note this article is 1. a sequel of the article below link. https://riichi-mahjong.com/2020/01/28/mahjong-strategy-push-or-fold-4-maximizing-game-ev/ and is 2. a summary and translation of Unimaru’s video on Youtube. To write this article, I got approval from him. Thank you, Unimaru san ! You can watch his video from the link below.

You may remember steps to judge Push or Fold, described on Part 1, which are

1. estimate deal in percentage
2. calculate round EV
3. calculate required point to push (this is round optimal)
4. consider winning value index (explain it later) to calculate game optimal required point to push.

This Part 2 article start from 3. and 7:06 of the movie. Here we go !

Now Unimaru tries to calculate the border line: lowest hand value with which we can push. According to his calculation, if we push 20% hitting tile, EV of 3,900/2,000/1,000 hand is -300/-800/-1000, all of them are better than EV of Betaori: discarding only safe tiles and giving up wining which is -1,100. So we can push with even 1,000 hand in case of Ryanmen Tenpai.

When our wait is not Ryanmen, EV of 8,000/3,900/2,000 hand is -100/-700/-1,300. (Please note previously mentioned on 3,900/2,000/1,000 hand and now on 8,000/3,900/2,000 hand )

So, when our wait is non Ryanmen, border line of our hand value to push 20% hitting tile is like 3,000.

And one more thing we should notice is these EV include 1,000: Riichi stick.

From 9:19 of the movie is about last part, 4.consider winning value index to calculate game optimal required point to push.

Winning value index is a multiplier to calculate the value of winning for each situation.From 10:03, he explains value of 8,000 for the player who has 10k and 50k is different. Former is higher because that 8,000 may raise his position. Winning value index tells us how much higher.

For example, if you are playing Tenhou, and 7 dan, and has 24k to 26k points at South 2, the index is 0.71.

This means the value of 7,700 hand (+1,000: Riichi Stick) here is equal to (7,700+1,000) x0.71=6,180 at East 1. This is larger than border line: 2,000, and you push here even if we consider Game EV.

Then how much value hand is on border line ? Let X be border line, X x 0.71=2,000. X≒2,800. So we can push 2,000 hand +1,000: Riichi stick, by a small margin. He did same calculation for non-Ryanmen Tenpai.

From 12:40, it is a kind of trailer. He explains he can make “Push/Fold table”, and all we have to do is 1. to memorize this table before the game, 2. to recognize winning value index before the round, and 3. to calculate deal-in probability during the game. He seems to have plan to upload a movie on this table.

Well, this is the end of the movie. Lastly let me introduce Unimaru’s Youtube channel. Definitely this is one of the best channels to learn Riichi Mahjong, and I recommend to subscribe, If you speak Japanese.

うに丸麻雀ちゃんねる

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