For a countably based space, choose a countable base containing the empty set and the whole set.
Possibly some of the tuples in this form may be discarded because one or more of their parts may be the empty set.
More precisely, when an address becomes unreachable, the set of values associated with it is reset to the empty set.
They each simply correspond to a different kind of set (empty set, singleton set, or set of cardinality 2 or more).
Accordingly, it would be unwise for a political theorist to dismiss the category of "unintentional restrictions of freedom" as an empty set.
Though it may be reasonable to interpret the completely undefined set as empty, it seems less intuitive that the empty set should be considered undefined.
Ignoring representation details for the moment, assume there is some representation of the empty set.
The empty set is not large because an orbit is by definition not empty.
