Suji: Difference between revisions

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→‎Basic Theory: try to reword the top sentence; also reword why suji tiles are safe

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 ==Basic Theory==
-In short: when an opponent discards a tile, the same-suit tiles that are 3 numbers away become safer against that opponent. However, if the tile you are discarding is a 4, 5, or 6, you need both possible tiles that are 3 away discarded (e.g. 4-sou needs both 1-sou and 7-sou discarded) to become safer. The explanation is as follows:
+In short: a tile become safer against an opponent ''if'' they have discarded every same-suit tile that is 3-apart from said tile. For example, if an opponent had discarded a 4, then both 1 and 7 of the same suit are safer. If an opponent discarded both 1 and 7, then the 4 becomes safer. The explanation is as follows:
 *The most common type of wait is an [[ryanmen|open]] [[wait]] (i.e. a [[ryanmen]] wait). An open wait is a wait that wins off two sides of a sequence, e.g. a hand containing {23}, or a hand containing {34}.
 *[[Shuntsu|Sequences]] are comprised of three sequential tiles. Therefore, an open wait will win off two tiles that are 3-apart. For example, a {23} ryanmen 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.
-*Therefore, if a tile in a suji interval is discarded, then other tiles in that interval become safer against that player. For example, if an opponent discards a 4, then the 1 of the same suit is safer. It would be impossible for them to have an open wait without entering [[furiten]]. Likewise, the 7 becomes safer when a 4 is discarded, due to the 4-7 interval.
+*Therefore, if every tile in a suji interval is discarded, then other tiles in that interval become safer against that player.
-**If a 1 is discarded, 4 does not become safer. There are two different intervals for 4: 1-4 and 4-7. Thus, after discarding a 1, it is not ''impossible'' for an opponent to have an open wait on 4; they could be waiting on the 4-7 interval. In order for 4 to be a "full" suji, both 1 and 7 have to be discarded. The same applies to 5 and 6.
+**If an opponent discards a 4, it is ''impossible'' for an opponent to have an open wait on 1 (without being in furiten). There is only one interval for the 1, that being 1-4, which is eliminated. Therefore, the 1 is safer against that opponent. Likewise, the 7 becomes safer when a 4 is discarded, due to the 4-7 interval being impossible.
+**If an opponent discards a 1, it is not impossible for an opponent to have an open wait on 4. There are two different intervals for 4: 1-4 and 4-7. After discarding a 1, an opponent could still have an open wait on 4-7 interval. In order for tiles numbered 4/5/6 to be a "full" suji, both 1 and 7 have to be discarded.
 Note: suji also applies to the other forms of furiten. So long as a given tile is 100% safe ([[genbutsu]]) against an opponent, you can use the suji of that tile. After an opponent declares [[riichi]], then any non-winning tile discarded by anyone becomes safe through furiten. Therefore, suji can be applied to those discarded tiles as well. So if an opponent declares riichi, and the next opponent discards a 4, then 1 and 7 are still considered suji.