Beginner Exercise 272 / Solution

Solution  

White's two stones on the left cannot approach the middle two black stones, but the stones on the other side can. removes that possibility. After , the white stones are dead.

This move doesn't help  

White shouldn't play : this is death in gote. It might look like seki, but the seki is only temporary: If played out (after the game or if forced), Black kills starting on a.