Can anyone give me an example of two sets A and B such that A intersection B is empty but A complement intersection B complement is not?

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- September 9th 2013, 12:43 AMjcir2826Sets
Can anyone give me an example of two sets A and B such that A intersection B is empty but A complement intersection B complement is not?

- September 9th 2013, 02:48 AMchiroRe: Sets
Hey jcir2826.

Let A and B = 0, A' and B = v. This means that (A and B) and (A' and B) = B = 0. So B is the empty set.

This means that for any A', A' and B = 0 since B is the empty set.

So its not possible to satisfy your condition. - September 9th 2013, 08:17 AMemakarovRe: Sets
I will also denote the complement of X by X'.

The OP needs A' ∩ B' ≠ ∅, not A' ∩ B ≠ ∅. Also, what is v and why is (A and B) and (A' and B) = B?

A' ∩ B' ≠ ∅ holds for most A and B, more precisely, unless A ∪ B is the whole universal set. So, you just need to find two small disjoint sets. - September 9th 2013, 08:25 AMPlatoRe: Sets
- September 9th 2013, 09:33 AMHallsofIvyRe: Sets
Let U= {a, b, c, d}, A= {a}, B= {b}. then A complement is {b, c, d} and B complement is {a, c, d}. There intersection is {c, d}.

In fact,**any**example where is not the universal set will do.