Suji: Difference between revisions

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{{Mahjong intervals|caption=Read the numbers across.}}
{{Mahjong intervals|caption=Read the numbers across.}}


'''Suji''' {{kana|筋}} is the principle of utilizing the "mahjong intervals".  This applies to the numbered suits: [[souzu]], [[pinzu]], and [[manzu]].  While these three suits are numbered 1 through 9, the numbers may be arranged in a square fashion to determine the "intervals".  The purpose is to deduce and/or determine tiles waiting via [[ryanmen|open]] [[machi|waits]].  The intervals themselves are based on the three-tile [[shuntsu|sequential groupings]]. Tiles along the intervals mark needed tiles to complete particular sequences.  Reading the numbers to the right across, the three main intervals are 1-4-7, 2-5-8, and 3-6-9.  Naturally, numbers within each interval can be paired such as 1-4 and 2-5.
'''Suji''' {{kana|筋}} involves the general inference of discarded tiles, when determining safe tiles.  The term alone points towards the principle of utilizing the "mahjong intervals".  This applies to the numbered suits: [[souzu]], [[pinzu]], and [[manzu]].  While these three suits are numbered 1 through 9, the numbers may be arranged in a square fashion to determine the "intervals".  The purpose is to deduce and/or determine tiles waiting via [[ryanmen|open]] [[machi|waits]].  The intervals themselves are based on the three-tile [[shuntsu|sequential groupings]]. Tiles along the intervals mark needed tiles to complete particular sequences.  Reading the numbers to the right across, the three main intervals are 1-4-7, 2-5-8, and 3-6-9.  Naturally, numbers within each interval can be paired such as 1-4 and 2-5.  Other references to suji are available, such as matagi suji and ura suji.


==Intervals==
==Intervals==
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Of course, one should not be necessarily dependent on these intervals alone, as some waiting patterns are immune to suji, such as a [[kanchan]] or [[shanpon]]. A [[toitoi]] hand is immune to suji.
Of course, one should not be necessarily dependent on these intervals alone, as some waiting patterns are immune to suji, such as a [[kanchan]] or [[shanpon]]. A [[toitoi]] hand is immune to suji.


Because of this, not all suji tiles are equally safe. Suji terminals (1 and 9) are the safest, as the only shapes that can be waiting on them are a [[tanki]] or [[shanpon]]. Nakasuji (4, 5, and 6) are the next safest, as they add the possibility of a [[kanchan]]. Suji 2 and 8 follow closely behind. This is because to have a kanchan on a middle tile, for example, a 4, they would have had a 135 shape in their hand. It's generally seen as better to wait with the 13 shape, since the 4 is more useful and less likely to be discarded, so a middle tile kanchan suji trap is slightly less likely. Finally, suji 3 and 7 are the most dangerous (though still reasonably safe), as they add the chance of a [[penchan]] wait.
Because of this, not all suji tiles are equally safe. Suji terminals (1 and 9) are the safest, as the only shapes that can be waiting on them are a [[tanki]] or [[shanpon]]. Nakasuji (4, 5, and 6) are the next safest, as they add the possibility of a [[kanchan]]. Suji 2 and 8 are roughly equivalent to nakasuji. Finally, suji 3 and 7 are the most dangerous (though still reasonably safe), as they add the chance of a [[penchan]] wait.
 
This doesn't apply to the riichi tile. The suji of the riichi tile is generally agreed to be dangerous, thanks to the strength of ryankan shapes. See the [[#Offense|Offense]] section for more information.
 
===28 Suji vs 456 Nakasuji Safety===
There are a few considerations about the relative safety of 28 suji and 456 nakasuji tiles.
 
In a game without [[Dora#Akadora|red fives]], the 456 tiles could be seen as safer. This is because to have a kanchan on a middle tile, for example, a 4, they would have had a 135 shape in their hand. It's generally seen as better to wait with the 13 shape, since the 4 is more useful and less likely to be discarded, so a middle tile kanchan suji trap is slightly less likely for this reason.
 
However, in a game with red fives, the player has an incentive to keep the red five. If they have a 135 shape, and the 5 is red, they would likely discard the 1 in order to keep the dora. Or, with a 246 shape, they could take the 46 shape and hope to win on the red five. 456 could be viewed as more dangerous in this ruleset, especially if you can't see the red five in the suit of your 2 or 8. As a side note, this is why the suji of a red five is seen as especially safe.
 
The [[dora]] itself can also change things. If the 1 or 2 is dora, the player would generally want to keep the 13 shape for the value, while if the 4 or 5 is dora, they would want to keep the 35 shape. This applies to the other suji shapes as well.


===Checklist===
===Checklist===
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A common way for this to occur is when a player has a ryankan shape, such as 468. They can discard the 4 to wait on 7, which is suji of the 4. Other players who know about suji may see this and be more likely to discard the 7. This is part of the reason why the suji of the riichi tile is considered dangerous.
A common way for this to occur is when a player has a ryankan shape, such as 468. They can discard the 4 to wait on 7, which is suji of the 4. Other players who know about suji may see this and be more likely to discard the 7. This is part of the reason why the suji of the riichi tile is considered dangerous.
== Other suji ==
=== Matagi suji ===
{{main|Matagi suji}}
'''Matagi suji''' is a concept that considers suji based on middle tiles discarded from potential sequences.  Given the discard timing, the individual tile may indicate suji intervals surrounding the tile.  However, this read can be difficult given other information on the board.
=== Musuji ===
=== Ura suji ===


== External links ==
== External links ==
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