Is there any such thing as a non-nested hierarchy? (I didn't see any question like this on the CSTheory exchange -- apologies if it has already been answered.)
In a nested hierarchy, a higher level includes all levels below it.
The classic example of a &quot;non-nested&quot; hierarchy is military rank.  A general is not a lieutenant, so military rank is a non-nested hierarchy.
But here's my objection -- doesn't a general have all the skills a lieutenant has, plus more skills?  So in that sense, isn't every general a lieutenant?  He may not be called &quot;lieutenant&quot;, but in reality he is a lieutenant-plus.
Thus, I am wondering... can we really say that any hierarchy is non-nested?
I think this question is more about the semantics of the english language than about cs theory. Unless this has a connection to some problem. I think generally speaking, hierarchy of things just means there is a well ordered relation of these things. And nested just means that the things are nested within each other. The relation is defined based on nesting. So the military ranks are a hierarchy, but not a nested one because the groups aren't nested within each other.