Armpit hit

    Keywords: MiddleGame, Shape, Tactics
[Diagram]
Armpit hit  

A move like W1 in the diagram to the left, a third line move diagonally under an opponents stone on the fourth line, is known as an armpit hit (so named because the reverse, black+circle played diagonally above W1, is a shoulder hit)

The armpit hit is usually a bad move, though in some special circumstances it can be proper (for example, a 3-3 invasion under a 4-4 stone is technically an armpit hit, but is played regularly)

To understand why the armpit hit is a bad move, we will first explore the general case of such an approach, know as the angle play.


Table of contents Table of diagrams
Armpit hit
Angle play
Angle play follow-up
Black's follow-up
White's follow-up
Further continuation
Joseki
Double hane joseki
[Pak Chi-eun] 8p (W) vs. [Rui Naiwei] 9p (B) 2008
[Zheng Hong] 7p (W) vs. [Cao Dayuan] 9p (B) 1992
Overconcentration
Game continuation


General Case - The Angle Play

In general, a diagonal approach to an opposing stone is what is known as an angle play. Angle plays are usually a little awkward, because the opponent has the local advantage of having sente in a symmetrical position. They are therefore usually special purpose moves.

[Diagram]
Angle play  

In this diagram, after W1, black will usually continue with either a or b. So black has the advantage of getting to choose the direction of play.

[Diagram]
Angle play follow-up  

After B2, white usually wants to continue with the stretch at a or the one point jump at b. In rarer circumstances, the hane at the head of one and a half at c may be good, although usually it is too risky because it is easy to cut.


Armpit Hit Continuation

[Diagram]
Black's follow-up  

In the case of the armpit hit, if black plays B2, the normal continuations of a and b are weak moves, because they are on the second or first line. The move at c is not as risky here, but is still on the second line.

Generally, the armpit hit is only playable if one or more of the following apply:

  • B2 is overconcentrated. This depends on the position to the left.
  • a, b or c are acceptable moves, for example to make quick life.
  • d is good, for example to make quick life again.
[Diagram]
White's follow-up  

W3 is a popular continuation of the armpit hit among beginners. This is, again, a bad move. White is pushing from behind and Black gets sente again in a symmetrical position, and can play a strong hane at the head of two with either of the points marked a, or stretch or jump with b or c.

[Diagram]
Further continuation  

Here is one possible continuation sequence. Note how white is getting pushed around, and at the end white's position still has weaknesses at a and b.


Exceptions

In some special cases, the armpit hit can be good. This depends on the surroundings

3-3 invasion

[Diagram]
Joseki  

Here, W1 is technically an armpit hit. But this invasion is seen regularly, so it can't be bad, can it?

Well, first thing to note is that the 3-3 invasion is bad when it is played too early. B2 and B4 are still good moves. Usually, the invasion W1 will be played when the resulting outside wall is overconcentrated, or easy to neutralize.

[Diagram]
Double hane joseki  

A second thing to keep in mind is that with the other edge close by, the double hane of B6 is not as good a move as it was earlier. Due to the closeness of the edge, white can cut and capture B6 here. If the edge was not so close, black would escape out with B6 and white's position would be a disaster.

Note: this line is still joseki, because black can cut at a and capture two stones. see 4-4 point 3-3 invasion double hane.


Quick life

[Diagram]
Pak Chi-eun 8p (W) vs. Rui Naiwei 9p (B) 2008  

Here, W1 by Pak Chi-eun is an armpit hit. The marked white stones are heavy, and are inside a strong black sphere of influence, so White wants to make life quickly. After B10, white has achieved this in sente.


Overconcentration

[Diagram]
Zheng Hong 7p (W) vs. Cao Dayuan 9p (B) 1992  

Here, B1 aims at forcing white into overconcentration. If white responds at a, his influence will overlap that of the strong white wall to the left, and White's stones are not being efficient. In the game, white therefore played b

[Diagram]
Overconcentration  

If white plays like this, the circle marked area is overconcentrated, and there is still the aji of the clamp at a.

[Diagram]
Game continuation  

Armpit hit last edited by 82.6.105.172 on January 31, 2011 - 01:36
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