broken ladder

   

Broken ladders

Examples of professional play

Almost an example of a ladder ko (as ko is only very near, but not affecting the ladder liberties itself) played by professionals, but most of all, the ladder is not working: [ext] broken ladder ex. 1 provided by Go4Go.net?.
I don't understand this part of the game. tderz

There is another example of a broken ladder between Feng Yun 9p and JZJ, 9p: broken ladder ex.2
I think to recall that Feng had Black and JZJ a moyo which Feng entered, where by a cutting stone was apparently controlled in a ladder.

Feng won the game because that ladder was broken and so JZJ's strategy.
However the most interesting point for me was, that Feng seemingly waited some moves before pulling out that stone (played some moves into the corner first, as she was seeking for live on the edge). I guess that was for maximising the dammage.
I sent her once an e-mail with that question, but of course Feng is very busy. I wrote already something here here on SL regarding that game. tderz


A ladder that is broken, although there is no ladder breaking stone

[Diagram]

A truly broken ladder.

The ladder is broken, so white cannot capture the marked black stones. Can you spot what breaks the ladder?

[Diagram]

Starting the ladder

This is the only way white can start the ladder.

Note that black cannot take the single stone in atari, as white could capture the black stones by squeezing from behind.

[Diagram]

Reaching the side

The stones on the side only turn the ladder.

[Diagram]

Along the edge

White can not steer the ladder away from its course

[Diagram]

Broken!

After B40, the corner stops the white squeeze. Black is safe!

[Diagram]

Broken?

[Diagram]

Broken? Ko. (Not that White can reasonably win this ko.)

Black would also play B42 at B44 to save a ko threat for later (just in case white _did_ have a million points threat somewhere.)

Black has two local threats (the other at a), but still this ko is losable, if there is some big semeai elsewhere.


This is a copy of the living page "broken ladder" at Sensei's Library.
(OC) 2012 the Authors, published under the OpenContent License V1.0.
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