Tile Theory at One-Shanten (2)
First, let us look at hands with too many blocks.
If you have fully absorbed everything up to this point, you should be able to derive the correct discard in every case on this page.
Example 1
Tsumo 
=> Discard
It is basic knowledge that a ryanmen wait is better than a kanchan wait.
Since drawing 
also creates a sanmenchan improvement, the basic discard order is first, then .
Example 2
Tsumo
=> Discard
This is a comparison between two kanchan shapes.
The double acceptance on 
is awkward, so cutting is correct.
Example 3
Tsumo
=> Discard
Chasing Iipeikou reduces the number of accepting tiles, and it is still inferior even after factoring in the extra value.
The correct answer is still to dislike the double acceptance on 
.
Example 4
Tsumo 
=> Discard
Both choices have the same acceptance count, 12 tiles, and both leave a kanchan wait. So the difference is not there.
Then what about the number of improvements into a better shape?
The manzu side only has one good-shape improvement: drawing to make a ryan-kan shape.
The pinzu side, by contrast, can improve with 
, which is much richer.
(Shanpon improvements are equivalent here, so they are excluded.)
There is a slight difference in how easy it is to win on kan 
versus kan , but the orthodox choice is still to value the number of improvements and drop the manzu side.
Example 5
Tsumo
=> Discard
This is a choice between two ryanmen taatsu.
It is a shape-reading mistake to think the side is worse just because you already use one yourself.
By discarding , the souzu side can become a ryanmen plus kanchan composite shape.
☆ Tsumo and you are in tenpai.
Example 6
Tsumo
=> Discard (or )
At first glance, it may look as though you could discard manzu, pinzu, or souzu.
However, if you drop the manzu side, then the reverse draw still remains an effective tile.
☆ Tsumo
If the table situation does not create a special difference, the correct move is to drop first.
This is a fairly fine point, so missing it is not a major disaster. Even so, keep the idea of covering a reverse draw somewhere in the back of your mind.
Original Japanese page: http://beginners.biz/pairi/pairi14.html