Tile efficiency: Difference between revisions

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[[Ukeire]], or tile acceptance, measures how many tiles can be used to reduce a hand's shanten. For example, a hand may have a tile acceptance of 40 tiles, meaning that there are 40 different tiles ''that can be drawn'' to advance the hand. The hand may have 10, 14, 16 distinct ''types'' of tiles that improve the hand, but "tile acceptance of 40" means there are 40 tiles that can physically be drawn.
[[Ukeire]], or tile acceptance, measures how many tiles can be used to reduce a hand's shanten. For example, a hand may have a tile acceptance of 40 tiles, meaning that there are 40 different tiles ''that can be drawn'' to advance the hand. The hand may have 10, 14, 16 distinct ''types'' of tiles that improve the hand, but "tile acceptance of 40" means there are 40 tiles that can physically be drawn.


Note: when measuring tile acceptance in actual games, it is important to note the amount of tiles actually available. Any tile discarded, used in your hand, used in an opponents call, or in the dora indicators can no longer be drawn, which affects the hand's tile acceptance. For example, a 67-pin ryanmen joint normally has an acceptance of 8 (four 5-pins; four 8-pins). However, if all four 5-pin and three of the 8-pin are discarded, the wait effectively has an acceptance of 1 tile.
Note: when measuring tile acceptance in actual games, it is important to note the amount of tiles actually available. Any tile discarded, used in your hand, used in an opponents call, or in the dora indicators can no longer be drawn, which affects the hand's tile acceptance. For example, a 67-pin ryanmen joint normally has an acceptance of 8 (four 5-pins; four 8-pins). If all four 5-pin and three of the 8-pin are discarded, the wait effectively has an acceptance of 1 tile.


==Important concepts==
==Important concepts==
The general ideas of tile efficiency are:
The general ideas of tile efficiency are:
*Discard the tiles that contribute the least to tile acceptance / have the fewest amount of upgrades
*Discard the tiles that contribute the least to tile acceptance / have the fewest amount of upgrades
*All else equal, prefer having better acceptance at 1-[[shanten]] over any other time
*Try to get a good wait at [[tenpai]]
*Try to get a good wait at [[tenpai]]
*Prefer ryanmen over other types of joints
*Prefer ryanmen over other types of joints
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===Five-block theory===
===Five-block theory===
"Five-block theory" states that a standard winning hand has five "blocks" - four groups + one pair. Each joint and sequence in the hand is considered a block. Pairs are also considered a block, since they can be turned into a triplet. When a hand has 6 blocks, one of them will eventually need to be discarded. Thus, it is good to build hands with 5 blocks in mind (i.e., having 6+ blocks is redundant).
"Five-block theory" states that a standard winning hand has five "blocks" - four groups + one pair. Each joint and sequence in the hand is considered a block. Pairs are also considered a block, since they can be turned into a triplet. When a hand has 6 blocks, one of them will eventually need to be discarded. Thus, it is good to build hands with 5 blocks in mind (i.e., having 6+ blocks is worse than 5 stronger blocks).


Example hand split into blocks:
Example hand split into blocks:
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However, once a useful tile is drawn, the hand with 6 blocks has to discard one of the blocks, lowering the efficiency in the future.
However, once a useful tile is drawn, the hand with 6 blocks has to discard one of the blocks, lowering the efficiency in the future.
Example 1-shanten hands:


{| class="wikitable"
{| class="wikitable"
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!# Pairs !! Shape !! Tile acceptance
!# Pairs !! Shape !! Tile acceptance
|-
|-
|1 || {{#mjt:23m22p78s0000000z}} || {{#mjt:14m69s}} (16 tiles)
|1 || {{#mjt:23m22p78s1000000z}} || {{#mjt:14m69s}} (16 tiles)
|-
|-
|2 || {{#mjt:23m22p778s000000z}} || {{#mjt:14m2p689s}} (20 tiles)
|2 || {{#mjt:23m22p778s000000z}} || {{#mjt:14m2p679s}} (20 tiles)
|-
|-
|3 || {{#mjt:223m22p778s00000z}} || {{#mjt:124m2p689s}} (22 tiles)
|3 || {{#mjt:223m22p77s00000z}} || {{#mjt:124m2p7s}} (12 tiles)
|}
|}


When you are likely to [[pon]] one of the triplets (e.g. [[yakuhai]] pair), then keeping 3 pairs can be good, since you'll be at 2 pairs once you make the pon.
When you are likely to [[pon]] one of the triplets (e.g. [[yakuhai]] pair), then keeping 3 pairs can be good, since you'll be at 2 pairs once you make the pon.


Also, when you have an open hand, keeping pairs is relatively stronger than normal. This is because you can pon with any player's discard, but [[chii]] can only be done to the player to the left. Pairs of tiles likely to be discarded, like guest winds or 1s/9s, are better.
Also, when you have an open hand, keeping pairs is relatively stronger than normal. This is because you can pon with any player's discard, but [[chii]] can only be done to the player to the left. When open, pairs of tiles likely to be discarded, like guest winds or 1s/9s, are stronger.


When you have too many pairs, it's often best to turn a 'ryanmen + pair' into a normal ryanmen (e.g. from 778, discard a 7 to get 78). Ryanmen are already good to wait on, so they do not need the "improvement" as much. Then, discard pairs  
When you have too many pairs, it's often best to turn a 'ryanmen + pair' into a normal ryanmen (e.g. from 778, discard a 7 to get 78). Ryanmen are already good to wait on, so they do not need the "improvement" as much. Then, discard pairs that are harder to form triplets/joints. With 6 blocks, discarding a pair outright is good.


If you have 4 pairs you might want to consider [[chiitoitsu]], but if a sequence or triplet forms, you should probably discard a pair and go for a normal hand. At 5 pairs, you're at 1-shanten for chiitoitsu, so you should likely go for that.
If you have 4 pairs you might want to consider [[chiitoitsu]], but if a sequence or triplet forms, you should probably discard a pair and go for a normal hand. At 5 pairs, you're at 1-shanten for chiitoitsu, so you should likely go for that.
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* {{#mjt:24m12345p5789s22z}} Draw: {{#mjt:4s}}
* {{#mjt:24m12345p5789s22z}} Draw: {{#mjt:4s}}


In this case, the 24-man [[kanchan]] is no longer useful to the hand. The hand will discard both 2-man and 4-man once it reaches tenpai. As the 4-man is a middle tile, it is more dangerous, so it should be discarded first.
Assume the red 5-man is unavailable. In this case, the 24-man [[kanchan]] is no longer useful to the hand. The hand will discard both 2-man and 4-man once it reaches tenpai. As the 4-man is a middle tile, it is more dangerous, so it should be discarded first.


* {{#mjt:24m12368p5789s22z}} Draw: {{#mjt:4s}}
* {{#mjt:24m12368p5789s22z}} Draw: {{#mjt:4s}}
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