**Question**

What do $R$, $R^2$ and $R^{-1}$ represent when $R$ is a relation on the set of natural numbers?

I'm doing some homework, but the $R^2$ and $R^{-1}$ notation confuses me.

Does $R^2 = R\*R$?

Does $R^{-1} = \frac{1}{R}$?