Beginner Exercise 2 / Solution

Solution  

After , White can't play at a because of shortage of liberties.

If White plays at b, Black can later play at a. White can then capture Black's stones, but that leaves her with a three in a row shape.

See also rectangular six in the corner.

Incorrect: leads to ko for life  

(The question says "kill White without ko".)

Variation  

What if White plays somewhere else?

If White answers with here, Black plays . White would like to play at as well, if Black plays at a or b. Why?

Bulky five  

Because if we add to the 2x3 square we get a shape called bulky five (marked). And that shape can be killed by playing on the vital point, marked with a square.

Bulky five (again)  

So, after and in the Variation diagram, we have a bulky five shape, with one point already occupied by Black. However, the vital point marked with a square has not been played yet. That is why Black plays at next. (And that is why White trying to live with in the first diagram seems like a good idea - but fails as well.)

Try to memorize the bulky five shape. It occurs over and over again.