91Ó°ÊÓ

List the members of \(\mathcal{P}(\\{a, b\\})\). Which are proper subsets of \(\\{a, b\\} ?\)

If \(X\) has \(n\) members, how many proper subsets does \(X\) have?

What relation must hold between sets \(A\) and \(B\) in order for the given condition to be true? $$ A \cap B=A $$