Eye in the belly

Eye in the belly  

A potential eye, such as this one at the marked point, may have a big effect on the almost filling of groups. It doesn't need to be a real eye to make a difference.

Real eye in the belly  

This is a simple capturing race, which Black has already won: his string forms an eye while White's doesn't: the internal liberties count for Black.

Eye in the belly - start  

In the previous diagram, Black's string formed a real eye but even false eye can do the trick.

eye in the belly - 1  

If White moves at , then turns the shape into a nakade: next he can almost fill with bulky five at a. If White plays at a, she dies in gote because the eyespace is almost filled with a farmer's hat.

eye in the belly - 2  

So what if White leaves this situation alone? Then Black can play at any time, starting to make a real eye in what used to be White's eyespace. Next, another move at a completes the eye. If White plays there, Black plays b and now the eyespace is almost filled with a bulky five.

Anyhow, the starting position is settled: White is dead.

Unsettled position  

In this case, with one more space inside, Black can kill by making the eye but White can make a seki.

White dies  

With Black makes a real eye in White's belly, just like in the second diagram from the top.

White can live in seki  

After White is alive in seki : Black cannot successfully fill White's eyespace and Black cannot make it a real eye anymore.

A famous problem regarding an eye in the belly can be found in the treasure chest enigma