I'm trying to learn about negative association of random variables. A definition can be found here: http://www.cs.cmu.edu/~dwajc/notes/Negative%20Association.pdf.

Now, consider the following question:

Let $X_1$, $X_2$ be independent but not necessarily identically distributed random variables. Let $σ_1, σ_2$ be a random permutation on $\{1, 2\}$. Are the variables $Y_i = X_{σ_i}$ negatively associated? Why?