the set of every set is that set
Empty set or null set
empty set is a set because its name indicate as it is the set.
The noun 'set' is a standard collective noun for:a set of bowlsa set of cutlerya set of dishesa set of golf clubsa set of knivesa set of mathematiciansa set of oystersa set of sailsa set of tires
set is a is a set
The collective noun for the noun china is a set of china.
The set contained in another set is termed as a sub-set.
The concept of closure: If A and B are sets the intersection of sets is a set. Then if the intersection of two sets is a set and that set could be empty but still a set. The same for union, a set A union set Null is a set by closure,and is the set A.
null set or empty set, is a set with no elements.
"What is the set of weights?" "What is the set of weights?" "What is the set of weights?"
That is the definition of a closed set.
sub set is set