Betaori
A player in betaori 「ベタ降り」 ("folding" in English) aims to minimize the chance of dealing into other players' hands, often giving up the chance to win in the process. While a player in betaori can still lose points to tsumo and tenpai settlements, more points will be lost by dealing in.
Overview
When playing betaori, you should discard the safest tiles first. This means discarding genbutsu (100% safe tiles) before "relatively" safe tiles like suji and honors, even if it would break a group or pair. Defense is often done against a single player, such as a player who declared riichi, but there are many cases where defending against multiple players is required.
Safe tiles
Determining safe tiles requires deduction from visible tiles, including all discards, dora indicator, and the tiles in the player's own hand. Of course, it also requires the player's active decision to defend (as opposed to continuing to push the hand towards tenpai).
From safest to least safe, where danger rating = deal-in% during mid-game:
- Genbutsu (0% danger): Tiles that would put a player in furiten are 100% safe against that player. This means any tile a player discards is 100% safe against that exact player. Also, after a player declares riichi, any tile anyone discards without a ron is 100% safe against the riichi-declarer.
- Honors with 3-4 visible (0.2%/~0% danger): In order to win on an honor tile, the hand must either have a copy of that honor or wait on the rare (and easily spotted) kokushi musou. Therefore, 3-visible honors are extremely safe, 4-visible honors are practically 100% safe.
- Honors with 2 visible (1.5% danger if 1 discarded; 3-4% danger if 0 discarded): 2-visible honors are relatively safe, around suji. They are more dangerous in the late-game.
- Kabe (1.5%-3% danger): When all four copies of a tile are visible, the same suit tiles towards the outside become safer kabe tiles. For example, if four 3-pin are visible, 1-pin and 2-pin are kabe tiles. This is because it is impossible for an opponent to have a ryanmen or kanchan wait on said tiles. Tiles towards the outside are safer.
- Suji (1.5%-4.5% danger): When a tile is genbutsu, the same suit tiles 3-away are safer suji tiles. This is because the most common type of wait (ryanmen wait) wins off of tiles that are 3-apart, which suji "blocks". Note that 4/5/6 tiles are extra dangerous, so in order to be "full" suji, they require both 3-away tiles to be genbutsu. Tiles towards the outside are safer.
- Sotogawa (3%-5% danger): When a tile is discarded early - within the first 6 or so discards - they are less likely to wait on same suit tiles outsisde the discard. For example, is 3-pin is discarded early, it's less likely for them to wait on 1-pin or 2-pin. This is because it's rare for an opponent to discard 3 from shapes like "233", "334", or "133", making a "23" or "34" in hand less likely.
- One chance kabe (5%+ danger): When 3 copies of a tile are visible, tiles towards the outside are safer, similar to regular kabe. As dangerous as regular tiles in the late game.
- Regular tiles (8-14%+ danger): Regular tiles are quite dangerous; honors and terminals are the safest, but even them are significantly more dangerous than suji.
When tiles are equally safe
If two tiles are equally safe, try to discard tiles that are more likely to be dangerous against the other players. For example, if both 6-pin and 1-pin are safe against a riichi player, discard 6-pin first. That way, if another player enters tenpai, the 1-pin in hand will be less dangerous.
If two tiles are still equally safe, it is best to discard a tile that does not reduce hand progress. After all, you can prevent opponents from winning by winning yourself.
Defending against 2+ players
Defending against two players is tricky, since defensive techniques like genbutsu and suji apply to each player individually.
Try to find genbutsu against 1 player (preferably the player who you want to deal into the least, e.g., the dealer), and of the tiles genbutsu against that player, find the tile safest against the other player. After a few turns, riichi furiten / temporary furiten should help generate tiles safe against both players.
Mawashi uchi
Mawashi uchi 「回し打ち」 is a strategy distinct to betaori. A "halfway" style, it aims to retain 1-shanten while discarding relatively safe tiles (e.g., suji, sotogawa tiles). A player undergoing mawashi will discard relatively safe tiles, even at the cost of tile acceptance.
When undergoing mawashi, you should constantly evaluate if you should be folding. If a dangerous tile is drawn and can't be used in the hand, mawashi will often convert to betaori (or sometimes convert to full pushing). If it gets too late in the round, it may also be good to fold, as it is easier to deal in when late in the round. Conversely, if you hit tenpai in a reasonable timeframe, pushing is generally good.
Because mawashi requires good push/fold judgement, it is recommended to learn how to betaori properly before mawashi (new players may discard recklessly, claiming it is "mawashi").
External links
- Written work on defense in Osamuko