To find sets A, B and C such that A ∩ B = ϕ , A ∩ C = ϕ and A ∩ B ∩ C = ϕ
Take A = {1, 2, 3}
B = {2, 4, 6}
C = {3, 4, 7}
Then,
A ∩ B = {2}
∴ A ∩ B ≠ ϕ
A ∩ C = {3}
∴ A ∩ C ≠ ϕ
C ∩ B = {4}
∴ C ∩ B ≠ ϕ
But A, B and C do not have no elements in common,
∴ A ∩ B ∩ C = ϕ.
