I was thinking how to formally express a set of the following property. First of all we have got a set of $i\in\{a,b,c,...\}$. Then we want to consider equations of an arbitrary form (say: $x_i\leq i'$), in which $i$ is included. However, we want these equations to exist only if a variable directly connected with $i$, call it $i'$ meets a certain condition (say: $i'>2$).
For example, we have got a set $i\in\{a,b,c\}$ and we know that $a'=3$, $b'=0$, $c'=6$. So that we will have the inequalities: $$x_a\leq 3$$ $$x_c\leq 6$$ (We don't want to have equation for $x_b$ as the condition $b'>2$ is not met.)
How to write it formally?
I have got an idea, however, I am not sure whether it captures the described abouve behaviour. $$x_i\leq i'$$ $$where:$$ $$i\in\{k\in\{a,b,c,...\}|k'>2\}$$
What do you think about it?
How about expressing your conditional values as another subscripted variable instead of a prime on the index?
"Let $A = \{a, b, c, ...\}$ and suppose that $x_i \le y_i$, for all $i \in A$ such that $y_i > 2$."