- In mathematics, the empty set is the unique set having no elements; its size or cardinality (count of elements in a set) is zero. Some axiomatic set theories ensure that the empty set exists by including an axiom of empty set, while in other theories, its existence can be deduced. Many possible properties of sets are vacuously true for the empty set.
- Cabinda Province (Wikipedia)
Cabinda (formerly called Portuguese Congo, Kongo: Kabinda) is an exclave and province of Angola, a status that has been disputed by several political organizations in the territory. The capital city is also called Cabinda, known locally as Tchiowa, Tsiowa or Kiowa. The province is divided into four municipalities—Belize, Buco-Zau, Cabinda and Cacongo.