The eye-stealing tesuji is a tesuji that prevents the opponent making a proper eye, leaving them at best a false eye.
A Go proverb says “Learn the eye-stealing tesuji” and it is indeed useful, not just to prevent eye-formation but also because it can force bad shape on the opponent.
The basic position
The marked stones show the basic situation. White 1 is the eye-stealing tesuji, taking away the potential eye at : a simple but very useful move. A Black play at instead would make an eye there for black.
The typical shape
The eye-stealing tesuji typically involves the following shape:
The point is the crucial point for making shape.
If White plays there, the shape is destroyed. Usually, the stone is in place, so that Black eventually will have to prevent the cut and connect at a, ending up with a clumsy shape.
Variants of the tesuji
Variants of the tesuji can occur in simpler situations:
Variant with fewer stones in place.
With in place, even after Black plays both , any one of a, b, c makes the eye false. White can play whichever is convenient and Black will have trouble defending them all.
The hanging connection
An eye can also be stolen from this hanging connection:
Black cannot get a real eye here; a and b are miai to make it false.
Playing an adjacent point
Sometimes White can play adjacent to , here or at a; in this case Black cannot even threaten to make an eye there. If possible, this may give White better shape, but the usual tesuji may be the only way to steal the eye.
Attacking a large group
In some cases, the tesuji can be the start of an attack on a large group. Consider this position which fairly often arises from a 33 invasion joseki:
This is not much of a threat in isolation, but if there are a few other white stones about or if it can be played as a ladder-breaker or a ko threat so White gets more than one move in the area, it might lead to an attack on the entire black group, perhaps splitting it into two weak groups.
tapir: Stealing an eye where black doesn't need one more eye isn't very useful, IMO. But the question is how to threaten the cut in the most beneficial way.
If the cut is something to fear for black (white stones along the left edge) may well gain something.
- The pages in the Eyes Collection.
- Protecting the cut - example 1.