Recent content by Stefan00

Thanks for you reply! That's where it get stuck I'm afraid, I cannot link the Union and Intersection to X with the given information. Stefan

@verty, thanks for your reply; So if A,B ∈ P(X) ⇒ A,B ⊂ X, and since every subset of X is in P(X), A∩B,A∪B are also in P(X)? Stefan

Let X be an arbitrary set and P(X) the set of all its subsets, prove that if ∀ A,B ∈ P(X) the sets A∩B,A∪B are also ∈ P(X). I really don't know how to get started on this proof but I tried to start with something like this: ∀ m,n ∈ A,B ⇒ m,n ∈ X ⇒ Is this the right way to start on this proof...