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Tripod Group
Path: LifeAndDeath   · Prev: BentFourInTheCorner   · Next: JGroups
  Difficulty: Beginner   Keywords: Life & Death

[Diagram]
Diag.: Tripod group

The black group in this diagram is called 'tripod group'. It is one of the smallest shapes in the corner that is alive as it stands. Black needs to remember the correct reply to two white attacks.


[Diagram]
Diag.: First attack

This is the first attack. After 2, Black still has a live shape in the corner.



Alain : This is true in most positions, but black should be careful when white plays in the neighbourhood!

[Diagram]
Diag.: Still some aji!

One should keep in mind that a white move at one of the marked points threatens to locally kill the corner. Of course, white has to be very strong at the outside if she wants to play like this.



[Diagram]
Diag.: Second attack


This is the second attack. In this context, Black must be careful not to make the following 'sente' exchange.

[Diagram]
Diag.: Black's mistake

The reason is that the status of the corner has now changed to ko. White can set up this ko following the next diagram.


[Diagram]
Diag.: White creates the ko

Black is now forced to win the ko if he wants to keep the territory in the corner.




[Diagram]
Diag.: The effect of the a-b exchange

The a-b exchange creates a shortage of liberties. After 5 in the previous diagram, if black hadn't exchanged a for b, he could live unconditionnally.

AlainWettach



[Diagram]
Diag.: This is unconditionally alive

[Diagram]
Diag.: This is unconditionally alive

The throw in at 4 is the key move. After 6, if white takes two stones at 'a', black will take back the white stone at 'a'.


[Diagram]
Diag.: This is unconditionally alive (black 8 at 4)

This variation with white 5 taking the ko results in the same result as the previous diagram - unconditionally alive.

--unkx80



[Diagram]
Diag.: What about ?

Yesterday 24/9/01 we practiced the TripodGroup at our club meeting. In response to White 1, Black 2 is the intuitive move for many players. We were wondering why this would be "wrong". I think that under these conditions, with all that open space around, this is actually a good move, but the tripod often appears in enclosed space, so that a White attachment at A becomes dangerous. Moreover, if there were an escape route along the left side, White would have blocked at 2 instead of 1. So, Black 2 at A is the main line.


[Diagram]
Diag.: One variation

[Diagram]
Diag.: Black dies

[Diagram]
Diag.: Black escapes but ...

So, Black escapes, but loses his corner territory and, what's more important, his EyePotential there.

--DieterVerhofstadt



Practical application

[Diagram]
Diag.: Application

This is a position from the final game of the 2000 German Championship, between Franz-Jozef Dickhut (Black) and Christoph Gerlach (White). Black wanted to do something about the upper left corner.


[Diagram]
Diag.: Invasion

So he invaded at 1. White can play 4 one point higher, but then Black has a cut at 4, which he can use to isolate the two white stones at the top. Either way Black creates a nice position.


[Diagram]
Diag.: Two points smaller corner

From an endgame point of view, it is better for White to play like this diagram: Black will end up with two points less in the corner. However in the game White followed the previous diagram, probably because he didn't like the remaining weaknesses on the left side following this sequence.
















--Stefan Verstraeten



Path: LifeAndDeath   · Prev: BentFourInTheCorner   · Next: JGroups
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