disjoint subset of random variables Can someone explain me (possibly with examples) the meaning of the following statement: X and Y are two disjoint subsets of random variables? what this disjoint means here? I understand what disjoint means in terms of events, i.e if And B are two disjoint events then $A \cap B=\emptyset $, but what that means in the context of random variables? Thanks
For what it is worth, I see no reason why this could refer to the hypothesis that every random variable in $X$ should be independent of every random variable in $Y$, nor to the hypothesis that $X\cap Y$ should be empty. If I had to bet, I would bet that this simply refers to two collections of random variables.

Or, one is given previously some set $Z$ of random variables and the hypothesis is that $X\subseteq Z$, $Y\subseteq Z$, and $X\cap Y=\varnothing$.
As per the definition random variable, the values the random variable can take should follow a determinable distribution. Hence this disjoint random variable may mean that the distributions of the two variables from which the two subsets are drawn from. Further the subsets themselves may be disjoint.