Miai (version 48)

Paths: <= Endgame => · <= Good Play =>

Difficulty: Intermediate Keywords: Tactics

|> Chinese: 见合 (jian4 he2)
|> Japanese: 見合い (miai)
|> Korean: 밋보기

Table of diagrams
Miai
Miai
Miai
Miai
Miai
Black's best move?
Double miai

! Definition of miai

The Japanese go term, adopted into English, miai denotes that a player has two different options at his or her disposal, such that, if the opponent takes away one, the player can take the other. Typically, if one player takes one option, the other player will take the other. Also, it typically does not matter which player gets which option.

For example, in this diagram White lives because if Black plays at a, White plays at b; and if Black plays at b, White plays at a, in both cases making two eyes. Unless Black plays here as a ko threat, we expect that this position will remain until the final stage of the game, when one player will get a and the other will get b, even if White plays first.

We say that a and b are miai for two eyes. In general any such situation where when one player takes or prevents one of two options, the opponent will play the other, is called miai. In English, the points are sometimes said to reflect each other. (Think of a see-saw.)

This might be the case in a local position like this, but also in more general, strategic concepts. For example, if Black has a large moyo which White can reduce or invade from two sides, the two invasions might be miai. For another good example of miai, see wariuchi.

Note that equivalence is an important aspect of miai. In miai positions, both the points are about the same in value, but they may not be exactly the same.

Usually, it is better not to play out miai points without additional reason. For example, in the situation above, a black move at a or b is sente. But playing it in the middle game is a loss of a ko threat which might prove to be decisive for the outcome of the game.

! Miai as a tool for problem solving

Example 1

Miai is not only an observation, something nice-to-know. Miai can be an effective tool when looking for a move. One cannot assume thoughtlessly that two moves are miai, but doing so can lead to the right move, and reduce the amount of thinking over a problem.

This diagram comes from Kanazawa Problem 1.

When White plays (mistakenly), an eye is created at the circled points. It is obvious that White could make a second eye at a if White was able to play at .

So Black plays at in order to prevent that. This is quite an obvious move for Black.

If White plays at here (mistakenly), the right place for Black to kill does not jump to the eye as easily as in the previous diagram.

Each of a, b, c and d deserve several seconds of thought... unless one thinks of the concept of miai.

If we think of the previous diagram - where White d was answered by - we might assume and d to be miai, and answer with Black d:

At this stage it is again obvious that, if White plays a, Black plays b.

So if White plays b first...

... Black answers at - again using miai reasoning.

The shape is a bent four in the corner and White is dead.

Example 2

Miai is indeed great for players with poor reading abilities. Here is a small example found in a Chinese tsumego book:

The goal for Black is to separate the white stones.

Obviously, this would generate a big profit for Black (territory in the corner and prisoners). How?

is the suji making respectively miai of a and b for connecting black+circle to the upper black group, and miai of c and d for cutting.

Of course, these points aren't strictly equivalent, since both players now want a and c in order to minimize loss/maximize profit. This is a mere detail compared to what is at stake.

But it does provide an "additional reason" for playing it out. If played out correctly, each player will get one play of a miai pair.

In this example, because it will be White's turn, we expect that White will seize a and c, leaving b and d for Black.

This is a useful example that shows the use of miai for attacking in a not-so-basic position.