So, I'm working on a relation proof, which is as follows.

Let < be the usual relation on Z. Prove that < o < is not equal to <.

So, I know that I want to prove that one is not a subset of another. And, I feel like multiplication can somehow be involved in this, but I'm not sure.

Please help guys. I'm retaking this class, and aside from set theory, this doesn't make much sense to me.