Prove: If , then is the smallest closed set containing .
So . We want to show that if is any closed set and , then .
So do proof by contradiction: Suppose that is not the smallest closed set containing . Is this the correct way to proceed?
Prove: If , then is the smallest closed set containing .
So . We want to show that if is any closed set and , then .
So do proof by contradiction: Suppose that is not the smallest closed set containing . Is this the correct way to proceed?