Beginner Exercise 53 / Solution

Solution  

It may look to be safe for Black - he has at least one eye in the left and a and b are miai for another. But....

, temporarily cutting Black in two, is a double purpose move. Now Black can't 1) form two eyes in the left by playing at both and c, nor 2) solidify the eye in the right for shortage of liberties.

Solution  

If Black solidifies the eye at a first by playing at , that group has only two liberties and it's White's turn, so White wins the semeai (capturing race).

Solution  

If Black tries to capture first with , White attacks the eye at . Black cannot solidify the eye at a because of shortage of liberties, and if Black captures the two white stones, the eye becomes false when White plays at a.

Failure  

here does not work - Black sacrifices the three stones to form two eyes in the left. at is met by at , securing another eye.