South 4 Strategy (3)
Let us look at several examples of tactical and situational judgment
under special South 4 conditions.
Of course, you will not often see a position that matches these examples exactly in real play.
What matters is understanding the way of thinking.
Practical Use of Declining Tenpai
In a flat game, I think it would be fine to cut the dora and riichi immediately.
But once you look at the score situation, you find that:
- even a mangan tsumo does not reach first place, so you need a hanetsumo
- and a direct-hit mangan from Kamicha drops you to third
That is the gap you are dealing with.
Once you take rank-based scoring into account,
cutting out the dora here probably brings more downside than upside.
So the best move is to twist the hand one step further and cut 
,
breaking tenpai on purpose.
That line guarantees full use of both dora,
and if souzu forms the head, you can still aim at a hanetsumo.
In this exact spot, that is the best play.
Passing on Ron
Passing on ron is a high-risk action,
but with an open hand it can still function as a strategy.
In South 4, you are only 2400 behind first place.
There should be no disagreement
that you should call this 
.
There is also still a 678 Sanshoku possibility.
After that, you take a 2000-point tenpai,
and then Toimen discards your winning tile.
There is no reason at all
to lay down your hand on this 
.
Since a tsumo or a direct hit can still take first place,
you should pass even if the winning tile comes from Toimen or Kamicha.
Declaring Noten
If declaring noten in South 4 still guarantees first place,
then even if you are actually in tenpai,
it is often the safest judgment to declare noten and simply end the game.
The score gap shrinks by 4000 when only one player is noten,
so if you are ahead by more than 4000,
it can be fine to fold a little earlier and head directly for an exhaustive draw.
In this position, a mangan tsumo by Shimocha overturns you,
so you are maintaining a no-yaku tenpai.
But Kamicha keeps hammering out genbutsu,
which makes it look as though they cannot build a hand and are already folding.
As long as Kamicha's last discard is not a dangerous tile,
I think declaring noten is completely fine here.
Of course, it is possible that you are simply unlucky
and Kamicha is actually in tenpai.
But with this point gap,
I think the danger of
"continuing the hand and then being overtaken"
is higher.
Helping Another Player Call or Deal In
If you are far ahead in first place,
then the thing you really fear is only the dealer continuing.
Of course, you do not need to obsess over continuances,
but sometimes you can actually raise your first-place rate
by helping another player.
In this problem, the key is how you read Shimocha's open hand.
The standard read would be:
"It is an ordinary cheap hand with no real comeback hope,
and the point gap with the dealer is also small,
so this is an opening made to protect second place."
If you can read it that way,
then cooperating with Shimocha is the correct judgment here.
Starting from a tile like 
,
just keep dealing out middle tiles one after another
and let them win with tanyao.
Even if they ron you,
it causes absolutely no problem.
Original Japanese page: http://beginners.biz/joukyou/joukyou09.html