Five Stones on the Second Line in the Corner

  Difficulty: Introductory   Keywords: Life & Death

As detailed in James Davies's Life and Death, five stones on the second line in the corner is the critical length and lives or dies according to sente. Shorter string die, longer strings live. For groups of stones on second line away from the corner see Six Die But Eight Live.

Straight five

[Diagram]
Straight five  

The usual vital point is a. If White plays there, she lives. If Black plays there, White dies.

Alternatively, b is also a vital point in this shape. A play by black at b forces white to make a bigger eye than otherwise necessary, which is a common strategy in life and death problems.

[Diagram]
Black can kill  
[Diagram]
White can live  


Bent five

There are two more shapes that might be referred to as bent five on the second line in the corner. One shape is symmetrical, each leg of the bent five having two stones; the other shape is asymmetrical (called Long L below), one leg having three stones and other leg having one stone.

[Diagram]
Symmetric 5  
[Diagram]
Symmetric 5  

Although black can play hane on both sides, blocking will allow white to keep two eyes.

See also: Gokyo Shumyo Section 1 Problem 1

[Diagram]
Mistake  

It is important that white does not let herself be tempted to play W1. After W2 and W4, the result is a bent four in the corner, and white is dead.

[Diagram]
Long L shape  

Normally, White can play at a to live with the maximum number of points. and Black can play there to kill.

[Diagram]
Long L shape  

On the rare occasion that both black+circle points are taken, W1 allows B2 to start a ko. If W3 at B4, then B4 at B6 leads to unconditional death.

In this case, W1 at W3 will give life.


See also:


Five Stones on the Second Line in the Corner last edited by Unkx80 on November 24, 2009 - 18:07
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