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Suji: Difference between revisions
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fix chiitoi spelling, minor "basic theory" adjustment, ura suji adjustment
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*[[Shuntsu|Sequences]] are comprised of three sequential tiles. Therefore, an open wait will win off two tiles that are 3-apart. For example, {23} can win off either a 1 or 4 of the same suit. {34} can win off 2 or 5 of the same suit. This continues until you get the intervals of: 1-4, 4-7, 2-5, 2-8, 3-6, and 3-9. | *[[Shuntsu|Sequences]] are comprised of three sequential tiles. Therefore, an open wait will win off two tiles that are 3-apart. For example, {23} can win off either a 1 or 4 of the same suit. {34} can win off 2 or 5 of the same suit. This continues until you get the intervals of: 1-4, 4-7, 2-5, 2-8, 3-6, and 3-9. | ||
*Due to the [[furiten]] rule, if a player has previously discarded any tile they could have won off of, they cannot win from other players. | *Due to the [[furiten]] rule, if a player has previously discarded any tile they could have won off of, they cannot win from other players. | ||
*This makes suji helpful. For example, if an opponent discards a 4, then the 1 of the same suit becomes safer against them. If they had a wait that wins off the 1-4 interval (such as {23}), then it would be subject to furiten | *This makes suji helpful. For example, if an opponent discards a 4, then the 1 of the same suit becomes safer against them. If they had a wait that wins off the 1-4 interval (such as {23}), then it would be subject to furiten (thus, unable to win off your discarded 1). Similarly, the 7 also becomes safer when a 4 is discarded, due to the 4-7 interval. | ||
Note: suji also applies to the other forms of furiten. After an opponent declares [[riichi]], then any non-winning tile discarded by anyone becomes safe. Therefore, suji can be applied to these tiles as well. If an opponent declares riichi, and the next opponent discards a 4, then 1 and 7 are | Note: suji also applies to the other forms of furiten. After an opponent declares [[riichi]], then any non-winning tile discarded by anyone becomes safe. Therefore, suji can be applied to these tiles as well. If an opponent declares riichi, and the next opponent discards a 4, then 1 and 7 are also considered suji. | ||
==Intervals== | ==Intervals== | ||
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== Defense == | == Defense == | ||
Suji implies that a player is using a [[ryanmen]] wait, or a related wait like [[ryanmenten]], [[nobetan]], or [[sanmentan]]. Ryanmen itself appears in around ~50% of winning hands, which is common, but not even close to guaranteed. Hands like [[toitoi]] and [[ | Suji implies that a player is using a [[ryanmen]] wait, or a related wait like [[ryanmenten]], [[nobetan]], or [[sanmentan]]. Ryanmen itself appears in around ~50% of winning hands, which is common, but not even close to guaranteed. Hands like [[toitoi]] and [[chiitoitsu]] are immune to suji. | ||
Note that the middle tiles (4,5,6) have two different suji intervals to account for. For example, 4 is part of the intervals 1-4 and 4-7. If an opponent discards a 7, the 4 isn't much safer, because the ryanmen of 1-4 is still present. In order to make 4 safer, both 1 and 7 must be safe. If both 1 and 7 are safe, then 4 is considered a nakasuji. The same applies to the other intervals. | Note that the middle tiles (4,5,6) have two different suji intervals to account for. For example, 4 is part of the intervals 1-4 and 4-7. If an opponent discards a 7, the 4 isn't much safer, because the ryanmen of 1-4 is still present. In order to make 4 safer, both 1 and 7 must be safe. If both 1 and 7 are safe, then 4 is considered a nakasuji. The same applies to the other intervals. | ||
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Say an opponent declares riichi on [[double riichi|turn 1]], discarding an honor tile, and your turn is next. If we assume the opponent has a ryanmen wait, there is only a 1/18 chance that any one of the untested suji intervals deals in. | Say an opponent declares riichi on [[double riichi|turn 1]], discarding an honor tile, and your turn is next. If we assume the opponent has a ryanmen wait, there is only a 1/18 chance that any one of the untested suji intervals deals in. | ||
If an opponent declares riichi after discarding 4-man, 2-pin, 6-pin, and 5-sou, then the following suji are safe: 1-4 man, 1-7 man, 2-5 pin, 3-6 pin, 6-9 pin, 2-5 sou, and 5-8 sou. This "eliminates" 8 suji intervals, leaving 10 intervals unaccounted for. Therefore, if we assume the opponent has a ryanmen wait, an untested suji has a 1/10 chance to deal in. | If an opponent declares riichi after discarding 4-man, 2-pin, 6-pin, and 5-sou, then the following suji are safe: 1-4 man, 1-7 man, 2-5 pin, 3-6 pin, 6-9 pin, 2-5 sou, and 5-8 sou. This "eliminates" 8 suji intervals, leaving 10 intervals unaccounted for. Therefore, if we assume the opponent has a ryanmen wait, an untested suji has a 1/10 chance to deal in. Basically, as more tiles become safe, the more dangerous the non-safe tiles become. | ||
== Offense == | == Offense == | ||
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=== Musuji === | === Musuji === | ||
Musuji {{kana|無スジ}} is a tile that is not [[genbutsu|100% safe]] and not suji. | Musuji {{kana|無スジ}} is a tile that is not [[genbutsu|100% safe]] and not suji. | ||
If an opponent discards multiple musuji tiles in a dangerous situation (e.g. after a riichi), then it's likely that they are in tenpai as well. | If an opponent discards multiple musuji tiles in a dangerous situation (e.g. after a riichi), then it's likely that they are in tenpai as well. | ||
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In the modern day, ura suji is often disregarded. If an opponent discards 5-pin early, then declares riichi, then non-suji 4-pin would be a dangerous tile. However, a non-suji 4-man, 5-man, 4-sou, etc. would also be dangerous tiles. Therefore, knowing about ura suji would not change your behavior. | In the modern day, ura suji is often disregarded. If an opponent discards 5-pin early, then declares riichi, then non-suji 4-pin would be a dangerous tile. However, a non-suji 4-man, 5-man, 4-sou, etc. would also be dangerous tiles. Therefore, knowing about ura suji would not change your behavior. | ||
*If you were folding, you | *If you were folding, you would not discard any non-suji unless you had to. | ||
*If you were attacking, you would discard ura suji anyways, because an ura suji is not that much more dangerous than a regular non-suji tile. | *If you were attacking, you would discard ura suji anyways, because an ura suji is not that much more dangerous than a regular non-suji tile. | ||
In addition, | In addition, ura suji assumes your tile is going for maximum [[tile efficiency]]. It also assumes that the 35 kanchan had existed in the first place. The 5-pin could have been an unrelated tile, or it could have been part of a 57 kanchan, or part of a 556 shape. | ||
== External links == | == External links == | ||