Beginner Tile Efficiency: Incomplete Set (Taatsu) Theory
We continue this week with xKime’s translation of Puyo’s blogs. This time we also have professional input from JPML’s Garthe Nelson, adding to the depth of the conversation. Hopefully some of these issues will bring some good conversation to the forums as well.
After we deal with the starting hand, we can assume all useless tiles have been taken care of. If the remaining tiles are not melds, we can divide them in the next three types:
1. Incomplete Sets (Taatsu): pre-shapes consisting of linked tiles, such as 2-3 or 2-4 which will eventually form a meld
2. Isolated tiles: Letter and number tiles that are alone
3. Pairs: Two of the same tiles paired up
The following text may explain the issues with Incomplete Sets/taatsu.
Types of Incomplete Sets/Taatsu
Taatsu may be open-ended (2-3), center-closed (2-4) or edge-closed (1-2), making it three types (namely open-ended (ryanmen), gut-shot (kanchan) and side waits (penchan)). Edge-closed shapes have the lowest value, then comes center-closed shapes, and open-ended shapes are the best. Therefore when you must abandon an incomplete set/taatsu, you should start by discarding the set with the lowest value.
In this hand what we should naturally discard is .
Now, when you must choose between two shapes of the same type, you must think about which one has the most chances of becoming good shape (i.e. open-ended).
Under these circumstances, we have two candidates: and . In appearance both the and 35 of dots are closed waits, but in reality there is a difference: can become open-ended with either the 
or 
, but , on the other hand, will become an edge-wait if you draw . Therefore the functionality of 2-4 is relatively lower to that of 3-5. To anticipate the opportunity of drawing , discard the first.
Therefore beginners should incorporate this sequence of values:
Listed as least valuable to most valuable
4. Edge waits (12, 89)
3. Closed Waits (13, 79)
2. Closed Waits (24, 68)
1. Open-ended Waits
From Garthe: The article concludes by saying beginning level players should use these guidelines as a way to decide which Incomplete Sets/taatsu to discard first when there are too many potential groups in the hand. In fact, a lot of advanced players would benefit from reviewing and reincorporating these guidelines back into their games as well.
Of course there will be times when we will want to choose an edge wait or closed wait over what might be a better closed or even open wait, e.g., we’re going for an Outside Hand or 3 Colored Runs, the bad wait uses Dora, etc. The reason the above is a good strategy “for the new guys” is that as a new player it’s hard to have a good feel for when the benefit of going for that more difficult Incomplete Sets/taatsu truly outweighs the benefits of going for the most likely one. These guidelines help you choose the most winnable sets and thus, by extension, the most-likely-to-get-you-to-ready-first. And even in Reach mahjong, the benefit of being the first to ready cannot be overstated, especially when hidden Dora and First Turn wins are allowed. Many a winning hand has been missed because some “advanced” player tried to get tricky and go for a big hand instead of a fast one. This is often a double edged sword as he not only missed the win, but may have allowed time for a bigger hand to catch up and win instead.
So caveat even for us know-it-alls, we ignore these guidelines at our peril. Choose wisely!
