Twisted four in the corner
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A twisted four which occurs in the corner may not be quite the same as the normal twisted four. The twisted four in the corner follows exactly the same logic as bent four in the corner.
Table of contents | Table of diagrams Fewer than two outside liberties Main line Two outside liberties Main line Main line Not Corner Twisted Four |
1. Fewer than two outside liberties
If there are fewer than two outside liberties, White can turn this position into a ko.
2. At least two outside liberties
If there are at least two outside liberties, Black is alive with three points.
kevinwm: Er... 4 points, yes? b captures 2 stones and has 3 territory, w captures 1 stone.
Karl Knechtel: Because White cannot kill, she will instead threaten to kill from the outside. Black will need a reinforcing move inside, and ends up simply with 3 points of territory - no captures involved.
Thanks to the two liberties, Black can play atari at
. Without one of those liberties, he would be putting himself into atari.
3. Endgame implications
When White reduces the outside liberties with ,
makes three points in gote, preventing the ko.
Side note: at a also lives, but is inferior to
because White would have a ko threat at
.
4. Corner Non-Twisted Four
The following is a Twisted Four and is in the corner but is not an example of what is meant by Twisted Four in the Corner. It is alive - a and b are miai:
See also:
Authors
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