Tile Theory at Two-Shanten (3)
This page covers two-shanten hands that do not fit the previous two standard patterns.
1. Four Taatsu Plus a Floating Tile
The key question in this shape is whether the floating tile should be kept.
Example 1
Tsumo
=> Discard
In a hand like Example 1, when you clearly have a weak taatsu such as
and the floating tile is part of a thick connected shape, you should keep without hesitation.
From a scoring perspective, the hand can also aim realistically at Tanyao, Pinfu, or Iipeikou.
Example 2
Tsumo
=> Discard
Here the floating tile still belongs to a strong connected block, so the weaker isolated tile on the other side should go first.
Example 3
Tsumo 
=> Discard
Once again, keep the stronger floating block and discard the weaker taatsu.
2. Headless Hands
When the hand has no pair yet, the comparison changes a little.
You still compare shape quality, but you must also remember that a head still needs to be formed somewhere.
Example 4
Tsumo
=> Discard
Although there is no head yet, the weak edge-side floating tile is still the natural discard.
Example 5
Tsumo
=> Discard
Even in a headless hand, the basic rule is still to discard the least useful floating tile first.
Change A
If you draw 
, then becomes more useful, so the balance shifts.
Change B
If you draw , the souzu side becomes much stronger, making the weak manzu tile even easier to cut.
3. Hands That Can Still Go to Chiitoitsu
Some two-shanten hands should also be judged from the perspective of a possible Chiitoitsu route.
Example 6
Tsumo 
=> Discard
Because the hand already contains useful pairs, do not destroy them too lightly if Chiitoitsu remains a realistic backup plan.
Example 7
Tsumo
=> Discard
The value of the existing pairs remains high, so the weakest floating tile still goes first.
Example 8
Tsumo
=> Discard
If the hand can still transition naturally toward Chiitoitsu, preserve that option unless there is a very strong reason not to.
Original Japanese page: http://beginners.biz/pairi/pairi12.html