Hane at the Head of Two Stones

  Difficulty: Beginner   Keywords: Shape, Tactics, Proverb

Chinese: 二子头必扳 (èr zǐtou bì bān) literally "two stones; must hane"
Japanese: 二子の頭は見ずハネよ (nimoku no atama wa mizu haneyo)
Korean: -

The head of two  

This proverb says that in a position like the one in this diagram, playing hane with Black a or White b (facing the center) is a very big move. If one is faced with a position like this, it is hardly ever good to play somewhere else on the board. The difference between these two moves is simply too large.

Black hane  
White hane  

Hane at the head of two stones  

Why is hane at the head of two stones so important? A typical sequence is B2 to B5. We observe the following:

  • White's influence increased significantly.
  • Black is pushed down with limited expansion? opportunities.
  • Black has a cutting point at a and the black+circle chain has only three liberties. This induces weaknesses around b (see eye-stealing tesuji), which is a burden to Black.

In some circumstances, W3 may choose to simply pull back at W5. But similar observations apply.

Enfors: More newbie questions: Wouldn't c be better than W5, to create two Tiger mouths, which would also protect the cutting point above c?

Dieter: whether a solid connection is better than a trumpet connection is a debate which is governed by the local, and most often even global situation. Basically, the trumpet connection is, as you say, locally connecting all stones, while the solid connection here will leave the other cutting point depend on a ladder. The drawback of a trumpet connection is that there are two peeping forcing moves available for the opponent, which potentially turn the whole construction into a dango.

There is some talk about this debate at the trumpet connection page, but I believe it is worthy of a page of its own. I'll leave this here for some time, then move it.

Enfors: Ah yes. I see now. At the time, I didn't notice that the cutting point left above c is ladderable.

tapir: Another issue for the trumpet connection is what happens after Black d. With a solid connection White most of the time will play hane, with a trumpet connection Black can cut in sente.

martin: Can black cut at B5 instead of extending at B4?

hyperpape: As always, it depends on circumstances, but Black has the isolated stone B4 and the cutting point at a after cutting and connecting. Unless getting the atari at d is necessary and valuable for Black, this will usually result in a local loss.

Hane at the head of two stones  

Author: AndreEngels, (WikiMasterEdit by Dieter).

Hane at the Head of Two Stones last edited by hnishy on November 15, 2020 - 02:51
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