I was told that such that and for which are not interchangeable, but I cannot determine which one to use. For example,
(a) The collection of numbers x for which x is even.
(b) The collection of all numbers x such that x is even.
I would probably go with (b) instead of (a), but I am not sure why. There are times when for which seems more appropriate, such as the following.
There are subsets of R for which the amount of time the orbit spends in those open sets is not proportional to the sizes of the sets.
When should I use such that or for which and when are they interchangeable?