Friday, 9 March 2012

Riichi theory(6): Tips to riichi

Source: http://blog.jpmahjong.net/read.php/620.htm

The previous articles introduced a few commonly seen examples of whether or not to declare riichi. Next, we'll discuss what tile you should declare riichi with.

It may seem like a trivial matter, but as the error piles up, it may adversely affect your results.

Choose the tenpai that lets you win easily
This can be considered a basic tenet of riichi, for example:


I believe that everyone would discard 4 sou and riichi.

Sometimes, a tile isn't necessarily easier to win on just because it's been discarded less. In the above example, even if a nan has been discarded and not a single 4 sou has been discarded, declaring riichi and waiting on nan is still the correct choice. A guest wind tile that has been discarded once is a very good wait.

What about this hand?


It's a no brainer to declare riichi here with dora 3. However, I'll only give you 90 marks if you declare 9 pin here. Personally, I would discard 2 wan here and wait on tanki 1 wan. Even though the number of tiles you can wait on is one lesser, there are two advantages in waiting for 1 wan.
1. 1 wan is more difficult to use compared to 3 wan, and it is much easier for it to be discarded. This effect is much more pronounced when the riichi is an early one and there are no safe tiles.
2. After discarding 2 wan, everyone will discard it as it's a genbutsu. 2 wan will gradually become kabe, thereby increasing the chances of someone discarding 1 wan.

The winning rate of 1 wan here should be higher than that of 3 wan.

Prioritize ankou of terminal tiles
Hands that do not have pinfu, should retain ankou of terminal tiles if possible. Like the following:


You should never discard 2 pin, but discard 3 pin here.
Terminal ankous are worth 8 fu, and the fu of the hand will be 40 fu if you get a tsumo. There's a difference between 1000 - 2000 points and 1300 - 2600 points.

Chance of ura-dora
Ura-dora is an important right of riichi, but a careless discard can affect your chances of getting ura-dora.


In normal situations, you would discard 5 wan and not 2 wan, and declare riichi. The hand is obviously aiming for ura-dora in order to reach mangan, and therefore should increase the chances of getting ura-dora.

However, there are exceptions to this.


The current round is all last and you're the dealer, the difference between you and the top player is 20000 points. Winning with a riichi tsumo mangan and getting a renchan in order to achieve gyakuten is a good idea, however, it would be perfect to get a tsumo haneman and achieve gyakuten in one shot.

Getting an ura-dora 1 would only mean an increase of 300 points, whereas ura-dora 2 gets you a haneman. Hence in order to increase the chances of getting ura-dora 2, it would be better to discard 8 wan here.

The next article will be about making decisions between han value and number of waits during riichi.

2 comments:

  1. "...even if a nan has been discarded and not a single 4 sou has been discarded, discarding nan is still the correct choice..."
    Should be " riichi and keep nan as a wait is still a pretty good choice"

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    Replies
    1. I've corrected the text. Thank you.

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