Originally Posted by

**bryangoodrich** I should probably rephrase what I said initially, because an intersection can be stated in a similar (and thus confusing) form: i.e., the intersection is what is common to each set. Therefore, the intersection of S, for some S = {a, b, c, ...} is what is common to *each* set a, b, c, ... In my initial phrasing, I am saying what is in the union of S is what is common among a, b, c; to be in the union is to be in *any* of a, b, c, ... Therefore, to rephrase, I should say the union is the set that includes all that is among the unioned sets. I believe this way better reflects the intuitive approach I had about dissolving the sets in the union, so that you are left with all that is among those sets.