Assertion: set's element | /r/HasProperty | empty set
Facets:
Source sentences:
text: Then {}, the set whose only element is the empty set, will belong to S 2 X; this is the von Neumann ordinal .
text: C(3, 0) = 1 subset with 0 elements (the empty subset),
text: The power set of the empty set is a singleton whose only element is the empty set.