/ Tenhou Review

Game Log 12:

Date: 17/08/21
Game Type: 特南喰赤
Link: http://tenhou.net/0/?log=2017082210gm-0029-0000-e75bb90f&tw=0
2位 A:Dasuke(+14.0) B:z9595451(-43.0) C:人型電脳和牌機(-25.0) D:ottosei(+54.0)

E2-0 11th-12th Turn

Do you think its worth slightly pushing a 1 shown yakuhai tile against a double riichi with a 1 shanten 1 dora hand on the 11th turn?
2017-08-21-01-01]
Probably, not only could this hand potentially get to tenpai in tile for ryuukyoku, but it could also become a Fighting hand with the right set of conditions.

Followed By: If you Did get tenpai on the double sided 8 unseen tile wait, would you take it?
2017-08-21-01-02
From a pure push/pull perspective, this isn't as bad as it looks actually. A good double sided wait hand with 1 dora and two riichi sticks on the field is actually Plenty to join the fray for a gain in EV compared to not taking this at all. Though, that's speaking only from a general perspective. If we look carefully at the board, specifically the number of double sided waits still dangerous out on the board to either player, we can see that there are ONLY 6/18 sujis left. With this few dropping a still live 8m, Especially since its usable by the Dora, is PRETTY DANGEROUS to say the least. If this hand was something like: 678m5678p5688899s then a riichi would be great, but in this case where the 8m is particularly very dangerous, it's probably best to play around by dropping the 9s.

S1-0 3rd Turn

This is a fun one, WWYD?
2017-08-21-01-03
So here we have a choice between dropping the 9m dora or a 2s. By keeping the 2s we gain additional chances to get pinfu tanyao with either 2s or 3s draws. By keeping the 9m there's the chance to get pinfu two dora. In either case, if 3p or 6p is drawn first, the highest EV choice following is to drop 2s/9m and declare riichi for the 47s wait. Since thats the case, there's no difference here outside of the benefit gained from either keeping the 2s, aka 23s draws, or the 9m, another 9m draw.

In the game I saw this as a choice betwen 7 tiles for two han, pinfu tanyao, vs 3 tiles for 3 han, pinfu two dora; as such I chose the 7 tile option.

THough putting this hand through Hitori Mahjong Simulator after the game, which won't be effected much since between 2s and 9m choice red 5 isn't partial to either, I was suprised to see this:
2017-08-21-01-04
2s drop has a higher EV! Why? Looking at the hand a bit closer theres another factor at play here, and thats the potential for iipeikou. With the 9m draw, it remains intact, in other words a chance for 4 han not including the riichi set (riichi, tsumo, ura dora, ippatsu). In the case of dropping the 9m and keeping the 2s, while a 2s is good for iipekou, a 3m draw actually removes the chance of it.

Its not a time deterent thing either, the EV of dropping the 2s staying higher than 9m all the way till 11th turn.

S2-0 11th Turn

Push or Pull?
2017-08-21-01-05
Looking at the Estimated Value for this situation, a general push pull rule is that one must have at least the estimated value of an opponents hand in order to fight with a bad wait and still win out over all. A non dealer riichi is estimated to have an average worth of 5000 points. Looking at our current hand, we have a bad wait 2k + 1k tenpai. Given our general rule of push/pull, this is a fold situation.