1) Begginers guide to defense Part 1
Introduction
I have seen alot of beginners in mahjong in tenhou, and what I see in common is the high 放銃率 or percentage of rounds that you deal in to a hand(or deal in rate). high deal in rate has the greatest effect to you average position or 平均順位.
Just as an example, this is my stats in jyoutaku in two seperate accounts that i have
First account
対戦数 116回
平均順位 2.120位
１位率 38.79%
２位率 26.72%
３位率 18.10%
４位率 16.37%
和了率 26.55%
放銃率 11.50%
立直率 18.77%
副露率 42.12%
Second account
対戦数 185回
平均順位 2.351位
１位率 29.72%
２位率 24.86%
３位率 25.94%
４位率 19.45%
和了率 24.76%
放銃率 11.81%
立直率 17.95%
副露率 38.99%
Although There is an element of luck in the average position and the number of times you win ( 和了率)(quite a big variation due to low number of hanchans played), you can see that 放銃率 stays pretty much similar. This is because there is less an element of luck in lowering this particular stat but skill.
Beginners I tend to find usually have high deal in rates 放銃率 of around +15% which is the primary reason , they do not get good results. Just as a reference, it is generally said that if you have 和了率 minus 放銃率 which is greater than 10%, it is good.
Terminology
Before actually going into the topic there are some terminology you have to know mainly suji and musuji
Sujis are the other wait of a certain tile when you consider a double sided wait, so for example suji of
is both
and
because you can have
wait or
double sided wait. Another example is suji of
is
and
because you can have either
double sided wait or a
double sided wait. Sujis are an important consideration in defense because of furiten. When a person riichi's, that person during riichi must win when the winning tile comes out, and if he does not, he becomes furiten meaning he cannot win off other players even if his winning tile comes out again (and can only win off tsumo). When predicting the wait of the person who riichis, you assume a double sided wait as around 60% of all riichi waits are double sided waits and therefore if the person who riichis does discards a
or some other player discards a
and the person who is riiching does not ron, you deem the suji of
,
and
safer (because it cannot be hit by a double sided wait due to furiten) than musuji. Musuji are tiles that is not yet a suji tile or a tile which the suji of it has still not passed against the riichi
The other type of sujis that you should know are double musuji, katasuji , nakasuji(or double suji). Double musuji are tiles with the number 4,5 and 6. It is considered a double musuji because these tiles can be hit by two variations of a double sided wait. eg.
can be hit by both
and
double sided wait whilst a normal musuji tile like
can only be hit by only one variation of double sided wait
double sided wait. katasuji (literally only one side suji) is when
is discarded against a riichi and it goes through,
is considered a katasuji as
double sided wait is now not possible but
is still possible (so only one side has been taken out of consideration). Nakasuji (literaly inside suji) you might have guessed is when both for example
and
has gone through against riichi so
cannot hit by any variation of a double sided wait. another example is if
goes through
is nakasuji.
Finally genbutsu tiles are the actual tiles that have gone through against a riichi. these tiles cannot be ronned due to furiten and therefore are completely safe against the guy who has riichied
Principles of Betaori
This certain skill called betaori is the most important tool in lowering your deal in rate. It means to throw away any chance of you winning your hand and just concentrate on not dealing into the opponent.
In jyou-taku (1st dan -3rd dan), the easiest rule you can follow to drastically lower your deal in rate and therefore hopefully increasing your average final position is to
Betaori if anyone riichis if you are NOT TENPAI
The most important point is that no matter how close you are to tenpai, IF YOU ARE NOT TENPAI, you should not push but should betaori. (SECOND TIME)
However there are exceptions to this rule(but I'll keep it simple)
1) you are iishanten (
with a hand you are likely to push once tenpai because you deem it good enough ), you can push sujis but no musuji until tenpai(explained in more detail in oshihiki post)
2) Once tenpai, you can push a musuji (but generally should not push double musuji(explained later) unless very early on or hand is high scoring or/and have a good wait)
3)Your are iishanten and if you have no or not enough (less than 2 or 3) actual safe tiles or suji tiles that you can bail and you deem that by bailing you are actually increasing your chance of dealing in, only then you can push a musuji ( you will not deal in if you win your hand, common situation with open hands) but once you have enough safe tile, immediately shift to betaori!
Do not however push any suji's before genbutsu if you are ryanshanten (two tile away from tenpai)
VERY IMPORTANT
How to Betaori
I am now going to give you a ranking for how safe a tile is against a riichi in order of safety
Completely safe - genbutsu tile
Class A - jihai that you can see three of
Class B - suji 1 and 9
Class C - jihai that you can see two of>jihai that you can see one of> nakasuji 4,5,6,
Class D - suji 2,8 > suji 3,7
Class E - musuji 1,9, > katasuji 5> musuji 28>katasuji 64 >musuji 37
Class F - double musuji 456
The way in which you Betaori is simple, you just throw away the tiles that you have in order of safety using this ranking.
jihais that are not yakuhai should be thrown first if same danger level due to points difference in case you get ronned
You should throw musuji 19 first then 28 then 37.
It is generally considered that from a menzen hand, if you have 3 genbutsu or suji tiles that are safeish, you can successfully betaori and avoid dealing in and therefore if someone riichis first and you have three safeish tiles you should betaori if you are not tenpai
I have put extreme emphasis on tenpai, but if you are tenpai, generally you can push unless it's a double musuji late on in the game (past 12th discard) but this will be explained in the oshihiki section so for now there is no problem in pushing any tile once you are tenpai, or you can bail whenever you feel like from tenpai using the safe tile ranking.
If you follow the rules and the order of safe tile discard you should be able to drastically lower you deal in rate to around at least less than 13% and be on the way to tokujyou (if you play tenhou)
Other Consideration
one chance - this is when three of a certain tile can be seen from the discard + your hand and you assume that the tile outside of that tile is safer because the chance of that tile you see three of has less chance of being in the hand of the guy who riichied and so cannot be used to form a double sided wait to ron you. This is better explained with examples. lets say someone riichied and you see 3
. You assume
are safer because to form a double sided wait to ron you on
, you must use the
in the form of either
and
respectively, but because you already see threem you deem unlikely that the person who riichied has the
tile in his hand and therefore you assume that
are safer than normal musuji tiles.
These rank a bit safer than their respective musuji tile if there was no onechance if it is within around the 8th discard but are generally more danjerous than suji tiles (so somewhere between Class E and D )
Kabe or wall - upgrade to one chance where you can see 4 of a certain tile so you are sure that the guy who riichied cannot form a double sided wait with the tile. eg 4
seen then
cannot be ronned by a double sided wait so it is safer than musuji tiles. Treat these as the same danjer ranking as the suji tiles of the respective number (1,9 = Class B, other =Class D)
Soku hikkake - this is when the suji of the riichi tile becomes more danjerous than normal suji tiles. This is because if you have
and you are tenpai, you riichi with the riichi tile as the
with a
wait. This is called a hikkake riichi. similarly if you have
, your riichi on the
to get a
wait. This is the reason why riichi tile's suji becomes slightly more danjerous than normal. However These suji's are still generally safer than musuji tiles.
Advanced techniques when desperate for safe tile
There will be many moments when your hand is just not good enough to push yet you have no safe tile. Even in these circumstances there is an order in which you should throw the tiles. I ranked the musuji tiles as 19>28>37 but this is only when you have equal number of these tiles in your hand. If you have only one 1,9, one 2,8 but three 3,7, you should actually throw the three 3,7 just because if the first one goes through you have another two tiles that are safe against the riichi.
eg
, from this hand if there are no suji or genbutsu tile, you should throw the
. similar rules or principle apply to suji tiles of the same danger rank
Defence against open hands (general)
This deviates from the Betaori topic and instead will consider defending against open hands.
The most simple rule is, unless you can clearly see or assume that the hand is expensive, you can ignore any naki or open hand and just push whatever tile.
ie let's say the dora is
and oya has ponned and chiied respectively in this order
and
, you can see that the oya is highly likely to have souzu in his hands and can easily use the
and the value of his hand will be 5800 which is expensive. even worse if he is using the
, it will be 11600. In these circumstances where you can see that a player is close to tenpai and has a very possible expensive hand and your hand is not good eneough to push, you should bail. similar circumstance occur when you see a dora yakuhai pon, you should try to bail against these hands as soon as this happens unless you have a very good hand
Defence against open hands (special cases)
1) defence against yaku back or atozuke
Lets say you have this particular hand in the 4th discard
tsumo
(dora
)
toimen who is in the south seat has chiied
in the east round and already there are
out and so if he has a yakuhai pair, it probably is the
that you have!
The discard you should make however is
in this case. The act of not throwing the
is called shibori, but this act is only disadvantageous to you because you lose one tile by keeping the
and the longer you keep it, the more likely you are going to be ronned on the
at the time of the disacard. The best solution is to ignore toimen and allow him to pon it if he can. The end result might be that he pons or maybe he doesn't but the end result for you is that you are likely to win your hand more by doing this by a slight amount. This is the key point, be selfish and increase the chance of you winning your hand at the cost of others in most cases.
2)Defence against iishokute of flush hands
Similar principles apply to in this case also, If your hand is good enough, you should throw any jihai or yakuhai against the player who is going for iishokute in the expense of others. exception is when you think the tile is going to be ronned at the discard rather than ponned.
The general rule for begginers is that you should assume tenpai or iishanten when if a player is going for let's say a manzu flush and manzu tile comes out. if jihai tile comes out, and the jihai is alive, (there less than two in the discard) you can also consider the player close to tenpai. From this point on unless you have a very good hand and your iishanten, you should generally not push manzu or jihai tiles which are still alive.
Thanks for reading ( and sorry for grammer mistake if any) will clarify and edit any explations or details if requested
(dora 
(dora 