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 of 2-2 is more emphasized and this time White kills the corner by playing at a. b and c may also kill depending on outside situations.

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, almost any move lives. If circle is occupied by a White stone, only a works.


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

Corner Vacant

[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.


Corner occupied

[Diagram]

White can kill

When the 4-4 point is occupied by White, 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 W1 and W3.


Discussion

[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


This is a copy of the living page "Weak Carpenter's Square" at Sensei's Library.
(OC) 2024 the Authors, published under the OpenContent License V1.0.
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