Taatsu Theory (3)
This page is about composite taatsu and how to handle them.
1. Ryanmen Plus Kanchan Shapes
Here we will look at six-tile composite taatsu such as
.
This shape has not only the ordinary acceptance on
,
but also the kanchan acceptance on 
.
This is a very common composite shape, so in real play you need to be careful not to overlook that kanchan acceptance.
Example 1
Tsumo 
Example 1 is a very famous discard-choice problem.
The correct answer is to cut and keep the kan 
acceptance.
Example 2
Tsumo Dora 
In Example 2, cutting turns the pinzu block into a ryanmen plus kanchan shape while still keeping the dora acceptance.
If the dora were not , then cutting and leaving the possibility of Iipeikou would also be a strong candidate.
2. Other Composite Shapes
Example 3
Tsumo 
Dora
If you cling to cutting because you want Sanankou or Iipeikou, that is too slow.
Even drawing makes the pinzu block tenpai, so this part should be kept as a thick shape.
The best discard here is .
Example 4
Tsumo Dora 
Cutting and keeping the kan 
acceptance is the best play here.
Of course, if the souzu block fills first, you would take the final wait as .
Still, compared with keeping a shanpon-style block, this line gives a higher chance of ending with Pinfu.
Other eight-tile composite shapes with eight tiles of acceptance include the following:
3m, 4-7m
2m, 3m, 1-4-7m
6m, 1-4m
1-4m, 5-8m
These shapes do not appear extremely often, but they are easy to misread, so you still need to watch for them.
Example 5
Tsumo
Here, the widest acceptance comes from simply tsumogiri-ing the .
That is because draws like
all turn the souzu block into tenpai.
If instead you cut or , the acceptance count drops by four tiles, so those choices are worse.
Original Japanese page: http://beginners.biz/pairi/pairi06.html