Weak Carpenter's Square

    Keywords: Life & Death
[Diagram]
Weak carpenter's square  

The weak carpenter's square is a carpenter's square without the connection at the corner of the shape. The vital point is the same, but this time White kills the corner by playing at a.

That is, without the black stone at circle, changes the status of the group from "White kills by ko" to "White kills unconditionally".

If Black plays first, then playing at a lives. Black lives with a even if circle is occupied by a white stone.

[Diagram]
White can kill  

After W9 a and b are miai: a White play at a creates a squared four, while a White play at b forces black to connect at c which reduces his eyespace to a bulky five.

[Diagram]
White can kill  

If B2 here, then W3 to W9 reduces the eyespace to rectangular six in the corner.



Table of contents Table of diagrams
Weak carpenter's square
White can kill
White can kill
White can kill
variation
Endgame technique
not really a carpenter's square
not really a carpenter's square


Discussion

[Diagram]
White can kill  

There are many ways for white to kill after W1. This is just one variation After W5, B6 at W7 is an auto atari so Black has no other option than to let white connect at W7.

[Diagram]
variation  

After W5 a and b are miai

[Diagram]
Endgame technique  

If Black has secured life by playing on the vital point, there is an important endgame technique for White to remember: the forcing moves at 1 and 3.


[Diagram]
not really a carpenter's square  

What about this one? Klaus



[Diagram]
not really a carpenter's square  

Here's one sequence. Bob McGuigan

Book references


Weak Carpenter's Square last edited by Unkx80 on February 19, 2018 - 21:06
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