Beginner Exercise 27 / Solution

Black saves the groups

Any a play is answered by either b; and vice versa. Thus Black secures eyes on the left group. So White attacks on the right. It looks like Black won't have enough eye space. But the cutting point (circled) proves fatal to White's plans.

Black saves the groups

threatens to capture and thus connect the groups, so White must fill. makes the necessary eyes.

Black saves the groups

Any other inside play, or a play at the squared point, is met by , which gives atari and also settles the eye space into a bent four. The circled points are miai to divide the space.

Black saves the groups

If White fills, Black can still claim enough eye space this way. In this variation White can't play at because of shortage of liberties, and Black captures to make two eyes.

Black saves the groups

Similarly here.

Black saves both groups

in the previous diagram is a mistake. Black should play atari instead, and then make two eyes with .

why can't black play at the cutting point?

The Count: Which point, when?

point 4 on the previous diagram become black's first move.

The Count: If was played at , White could immediately capture by playing one point higher.

Does this work?

How does this work? The ko threat at forces White to respond by filling in the ko, allowing Black to play a and secure the second eye. Anything I missed in this sequence?

Superdave: White would play at a, taking away the second eye. Why do you consider a ko threat?

Because of the ko. Black threatens recapturing the ko which puts the marked group in atari. But yeah, obviously white has sente which allows for the kill at a.

Superdave: White would just connect when Black takes back the ko, and it still wouldn't make an eye. In any case, a sure thing is better than a ko.