Farmer's Hat
The farmer's hat refers to the shape of stones or empty points that form the shape as shown in this diagram.
It is used to denote either a killable eye shape or a bad shape.
Table of contents | Table of diagrams The farmer's hat The farmer's hat Almost fill Almost fill The farmer's hat Very bad shape for Black Black cannot cut at 'a' |
1. The farmer's hat as a killable eye shape
The farmer's hat is a basic idea in life and death, it is a big eye with a being the vital point. If Black plays at a, he as three eyes; and if White plays at a, Black is dead. The farmer's hat has five inside liberties.
After White occupies the vital point, it is possible to almost-fill the shape into the straight three dead shape.
Alternatively, it is possble to almost-fill into bent three.
See also
2. The farmer's hat as a bad shape
The farmer's hat is a bad shape, for the same reason that the empty triangle is bad. You can think of this shape as two empty triangles.
The liberty at a (and similarly for b) is inefficient (see the empty triangle is bad page for more details).
If White plays at a or b, it actually would improve Black's shape. If both points are filled by White then the shape is really good.
In situations like this, the farmer's hat is really ridiculous.
The stone has to be at a.
Black's bad shape allows White to play . Black cannot cut at a. Furthermore the
point is a false eye.
Authors