Open and bounded sets seem to be abound (no pun intended), but I cannot think of any examples of closed and unbounded set, except for the trivial R and null sets.
Open and bounded sets seem to be abound (no pun intended), but I cannot think of any examples of closed and unbounded set, except for the trivial R and null sets.
Do you know of any such sets?
Any interval of the form [a,oo) or (-oo, a] is closed and unbounded.