Set Theoryhard
0:00.0

Let f:XYf: X \to Y be a function. For any subsets A,BXA, B \subseteq X, let f(A)f(A) denote the image of AA under ff. Which of the following conditions on ff is both necessary and sufficient for the identity f(AB)=f(A)f(B)f(A \cap B) = f(A) \cap f(B) to hold for all subsets A,BXA, B \subseteq X?